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  • 2020-2024
  • 1975-1979  (148)
  • 1890-1899
  • 1979  (148)
  • Molecular Cell Biology  (148)
  • 101
    Electronic Resource
    Electronic Resource
    Polyoma T (tumor) antigen species in abortively and stably transformed cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 127-137 
    Details
    ISSN: 0091-7419
    Keywords: polyoma virus ; middle ; and small tumor antigens ; ts-a ; hr-t ; abortive transformation ; transformed cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Stable neoplastic transformation of cells by polyoma virus requires the participation of two viral genes, designated ts-a and hr-t. The effects of mutations in these two genes on the patterns of T-antigen synthesis during productive infection have been previously described: ts- a mutants are affected in the “large” (100K) nuclear T antigen, and hr-t mutants are affected in the “middle” (36K, 56K, 63K) and “small” (22K) T agtigens. The latter are associated predominantly with the plasma membrane (56K) and cytosol fractions, rrespectively.Here we examine the expression of the various forms of polyoma T antigen in nonproductive infection (abortive transformation) as well as in stably transformed cell lines of different species. The results on abortive transformation are essentially the same as those described above for productive infection. In stably transformed cells, the middle and small T antigens are seen to various extents. The large T antigen, however, is often absent or present below the level of detection. Clones lacking the large T antigen are found most often among mouse transformants, but are also seen among rat transformants. Retention of the 100K species in transformed cells therefore appears to be, at least in part, an inverse function of the level of permissivity of the host toward productive viral infection. These findings indicate that the induction of the transformed phenotype in both abortively and stably transformed cells generally does not require the large T antigen, but rather the products of the hr-t gene.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120110
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  • 102
    Electronic Resource
    Electronic Resource
    7-Acetylcytochalasin B: Differential effects on sugar transport and cell motility (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 185-194 
    Details
    ISSN: 0091-7419
    Keywords: cytochalasin B derivative ; cell motility ; sugar transport ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cytochalasin B (CB) is a potent inhibitor of sugar transport and cell motility in animal cells. We have synthesized and characterized the CB derivative 7-acetylcytochalasin B (CBAc) and have found that it has differential effects on transport and motile processes in fibroblasts. The derivative inhibited sugar transport in human red cells, 3T3 cells, and chicken embryo fibroblasts at micromolar concentrations, although it was less potent than its parent compound. Unlike CB, which causes fibroblasts to round up and arborize at less than 10 μM, CBAc had no effect on fibroblast morphology and membrane ruffling at concentrations as high as 90 μM. Competitive binding experiments using [3H] CB showed that the affinity of CBAc for sites related to sugar transport in the red cell membrane is about one-fourth of that of CB. In contrast, similar experiments using [3H] dihydrocytochalasin B (a derivative which inhibits cell motility but not sugar transport) showed that the affinity of CBAc for sites associated with red cell spectrin and actin is only about 1/20 of that dihydrocytochalasin B. This study demonstrates that acetylation of the C-7 hydroxyl group of CB reduces its effect on cell morphology and motility much more than its ability to inhibit sugar transport. This observation, together with our earlier work with dihydrocytochalasin B, establishes that the pharmacologic effects of CB on fibroblasts result from the binding of the drug to two distinct classes of receptors and that these receptors interact with different parts of the cytochalasin molecule.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120205
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  • 103
    Electronic Resource
    Electronic Resource
    NMR of fd coat protein (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 139-145 
    Details
    ISSN: 0091-7419
    Keywords: fd coat protein ; 1H NMR ; 13C NMR ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The conformations of the major coat protein of a filamentous bacteriophage can be described by nuclear magnetic resonance spectroscopy of the protein and the virus. The NMR experiments involve detection of the 13C and 1H nuclei of the coat protein. Both the 13C and 1H nuclear magnetic resonance (NMR) spectra show that regions of the polypeptide chain have substantially more motion than a typical globular protein. The fd coat protein was purified by gel chromatography of the SDS solubilized virus. Natural abundance 13C NMR spectra at 38 MHz resolve all of the nonprotonated aromatic carbons from the three phenylalanines, two tyrosines, and one tryptophan of the coat protein. The α carbons of the coat protein show at least two different classes of relaxation behavior, indicative of substantial variation in the motion of the backbone carbons in contrast to the rigidity of the α carbons of globular proteins. The 1H spectrum at 360 MHz shows all of the aromatic carbons and many of the amide protons. Titration of a 1H spectra gives the pKas for the tyrosines.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110204
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  • 104
    Electronic Resource
    Electronic Resource
    Properties of epithelial cells cultured from human carcinomas and nonmalignant tissues (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 147-166 
    Details
    ISSN: 0091-7419
    Keywords: carcinoma and nonmalignant cells ; fibronectin ; human epithelial cells ; plasminogen activator ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human epithelial cell cultures were examined for expression of plasminogen activator and fibronectin matrix. All of the cells examined showed ultrastructural evidence suggesting their epithelial origin, including microvilli and specialized junctions. The nonmalignant cells were also negative for endothelial cell markers (ie, they lacked factor VIII antigen, a nonthrombogenic surface and Weibel-Palade bodies). The nonmalignant lines all produced large amounts of plasminogen activator, whereas the tumor-derived lines showed a gradation of activities, ranging from lines having as much activity as the nonmalignant lines to lines having little or no activity above background. For both normal and malignant cells, addition of dexamethesone only slightly decreased the levels of plasminogen activator. By immunofluorescence microscopy, normal bladder and fetal intestine epithelial cells showed fibronectin in a globular and fibrillar matrix. In contrast, normal mammary epithelial cells had a much diminished amount of fibronectin with a punctate distribution.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110205
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  • 105
    Electronic Resource
    Electronic Resource
    Mitotic factors from mammalian cells: A preliminary characterization (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 189-195 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The objective of this study was the preliminary characterization of the factors from mitotic HeLa cells that can induce meiotic maturation in Xenopus laevis oocytes. We found that this factor is a heat-labile, Ca2+-sensitive, nondialyzable protein with a sedimentation value of 4-5S. Furthermore, no new protein synthesis was found to be required for this mitotic factor to induce maturation in the amphibian oocytes. These data suggest that the factors involved in the breakdown of nuclear membrane and the condensation of chromosomes that are associated with three different phenomena, mitosis, meiosis, and premature chromosome condensation, are very similar in different animal species.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110208
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  • 106
    Electronic Resource
    Electronic Resource
    Pyrimidine biosynthesis in normal and transformed cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 197-205 
    Details
    ISSN: 0091-7419
    Keywords: pyrimidine biosynthesis ; V79 ; IARC19 ; IARC20 ; IARC28 ; biomarker ; pleiotropy ; confluence ; rat liver epithelial cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have developed procedures for sensitive measurement of specific radioactivities of pyrimidine nucleosides excreted from cells in culture. The changes in the observed values reflect dilution of the added isotope through de novo biosynthesis of nonradioactive pyrimidine nucleosides or by shifting and equilibration of other nucleotide pools into the free uridine pool. It is thus possible to monitor uridine biosynthesis occurring in intact cells without destroying or disrupting the cell population. On comparing a series of normal and transformed lines, we have observed several growth-dependent patterns of change in specific activity and levels of uridine excretion and the temporal appearance of these changes.Hamster embyro fibroblasts slows pyrimidine biosynthesis at mid-growth while the hamster cell line V79 continues to dilute the pyrimidine pool at about 7% of the rate observed during exponential growth at confluence. Both cells exhibit Urd excretion beginning at one-half maximal growth.Passageable normal rat liver cells (IARC-20) also show a cessation of pyrimidine biosynthesis with a prior increase in uridine excretion. Two chemically transformed lines IARC-28 and IARC-19 derived from IARC-20 show different patterns. IARC-19 begins uridine excretion in early log growth and the specific activity continues to decrease at about 2% of the rate observed during exponential growth at confluence. The IARC-28 cells also begin excretion in early log growth but pyrimidine biosynthesis stops at about midlog. This method may prove to be an additional aid in recognizing and differentiating transformed cells in culture that do not exhibit the transformed phenotype.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110209
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  • 107
    Electronic Resource
    Electronic Resource
    Isolation and characterization of a variant of B16-mouse melanoma resistant to MSH growth inhibition (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 251-258 
    Details
    ISSN: 0091-7419
    Keywords: tumorigenicity ; cyclic AMP-dependent protein kinase ; tyrosinase MSH-growth-resistant variant ; mouse melanoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A variant of B-16 F1 mouse melanoma was selected for its ability to survive and replicate in the presence of melanocyte-stimulating hormone (MSH). Although the variant (MR-4) was completely resistant to growth inhibition by MSH, cyclic AMP was still able to block cell replication. Tyrosinase activity in MR-4 cells was considerably lower than in B-16 F1 cells. MSH induced a twofold to three-fold increase in tyrosinase activity in both cell types, but the absolute activity in MR-4 remained significantly less than in the parental cells. MR-4 cells were also found to have a markedly depressed cyclic AMP-dependent protein kinase activity relative to B-16 F1 cells. The protein kinase from both cell types was stimulated by cyclic AMP, but the level of MR-4 kinase activity at maximal cyclic AMP concentrations remained considerably lower than B-16 F1 kinase activity under the same conditions. In both cell types adenylate cyclase activity was markedly stimulated by MSH. When equal numbers of viable F1 and MR-4 cells were injected subcutaneously into C57/B1 mice, the MR-4 cells formed tumors earlier and killed the host sooner than the parental F1 cells. We conclude that the biochemical alteration which allows MR-4 cells to replicate in the presence of MSH is a low level of tyrosinase activity, which in turn may be the result of low cyclic AMP-dependent protein kinase activity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110214
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  • 108
    Electronic Resource
    Electronic Resource
    Masthead (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979) 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110301
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  • 109
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    Erratum (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. i 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110302
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  • 110
    Electronic Resource
    Electronic Resource
    Fibronectin associated with the glial component of embryonic brain cell cultures (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 269-281 
    Details
    ISSN: 0091-7419
    Keywords: fibronectin ; cell fractionation ; glial fibrillary acidic protein ; immunofluorescent labeling ; neuronal-glial cell interactions ; brain cell culture ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In a basic approach to investigations of neuronal-glial interactions during both normal brain development and its pathogenesis, embryonic brain cell populations were fractionated into purified neuronal and glial components. Using separation procedures based on differential adhesion and cytotoxicity, the isolated neuronal and glial phenotypes could be identified by distinct morphological and biochemical characteristics, including the visualization of glial fibrillary acid protein (GFA) within glial cells in immunohistochemical assays with monospecific anti-GFA serum.When unfractionated cerebrum cells dissociated from 10-day chick or 14-day mouse embryos were plated as monolayers and cultured for 1-14 days, monospecific antiserum against fibronectin (LETS glycoprotein) was found to react with many, but not all, of the cells as revealed by indirect immunofluorescence microscopy. The isolated neuronal and glial components of these populations were used to determine whether the appearance of membrane-associated fibronectin was characteristic of one cell type or the other, or both, and if neuronal-glial cell interaction was required for its expression. It was found that the surfaces of glial cells, completely isolated from neurons, showed an intense fluorescent reaction to the anti-fibronectin serum. In contrast, the purified neuronal cultures showed no fluorescence with either the anti-GFA or anti-fibronectin sera. These results demonstrate fibronectin as a cell surface protein associated primarily with glial cells and independent of neuronal-glial cell interaction for its expression. Furthermore, the results indicate that the fibronectin observed on glial cell surfaces in these cultures is produced endogenously and is not due to the preferential binding of fibronectin present in the culture medium. The role of fibronectin as an adhesive molecule in neuronal-glial interactions is discussed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110216
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  • 111
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    Erratum (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 319-319 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110306
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  • 112
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    Specific interaction of cytochalasins with muscle and platelet actin filaments in vitro (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 283-293 
    Details
    ISSN: 0091-7419
    Keywords: cytochalasins ; muscle and platelet actin ; microfilaments ; cell motility ; viscosity changes ; electron microscopy ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The cytochalasins (CE, CD, CB and H2CB) inhibit numerous cellular processes which require the interaction of actin with other structural and contractile proteins. In this report we describe the effects of the cytochalasins on the viscosity and morphology of muscle and platelet actin. The cytochalasins decreased the viscosity of F-actin solutions. The effect of H2CB, CB and CD on F-actin viscosity was maximal at concentrations of 20-50μM and did not increase with time. In contrast, CE caused a progressive decrease in the viscosity of F-actin solutions which was dependent upon the concentration of CE and the duration of incubation of the CE-actin mixture. After two hours of incubation of drug-actin mixtures, the relative effectiveness of the cytochalasins in reducing the viscosity of F-actin was CE 〉 CD 〉 CB = H2CB. The effects of CD and CE were paralleled by morphologic changes in negatively stained actin filaments. The effects of the cytochalasins on the viscosity and morphology of muscle and platelet actin were the same whether the drugs were added before or after the polymerization of the protein.These studies show that the interaction of the cytochalasins with actin is highly specific. Because the relative potencies of these drugs for affecting motile processes and the relative affinities of the drugs for binding sites within a variety of cells are CE 〉 CD 〉 CB = H2CB, the effects of cytochalasins on actin described here may contribute to some of the biological effects of the drugs on motile processes.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110303
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  • 113
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    Fibronectin and proteoglycans as determinants of cell-substratum adhesion (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 401-427 
    Details
    ISSN: 0091-7419
    Keywords: fibronectin ; glycosaminoglycans ; proteoglycans ; adhesion ; substrate-attached material cytoskeleton ; immunofluorescence ; heparan sulfate ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: When normal or SV40-transformed Balb/c 3T3 cells are treated with the Ca++-specific chelator EGTA, they round up and pull away from their footpad adhesion sites to the serum-coated tissue culture substrate, as shown by scanning electron microscope studies. Elastic membranous retraction fibers break upon culture agitation, leaving adhesion sites as substrate-attached material (SAM) (Cells leave “footprints” of substrate adhesion sites during movement by a very similar process.) SAM contains 1-2% of the cell's total protein and phospholipid content and 5-10% of its glucosamine-radiolabeled polysaccharide, most of which is glycosaminoglycan (GAG). By one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, there is considerable enrichment in SAM for specific GAGs; for the glycoprotein fibronectin; and for the cytoskeletal proteins actin, myosin, and the subunit protein of the 10 nm-diameter filaments. Fibrillar fibronectin of cellular origin and substratum bound fibronectin of serum origin (cold-insoluble globulin, CIg) have been visualized by immunofluorescence microscopy. The GAG composition in SAM has been examined under different cellular growth and attachment conditions. Heparan sulfate content correlates with glycopeptide content (derived from glycoprotein). Newly attaching cells deposit SAM with principally heparan sulfate and fibronectin and little of the other GAGs. Hyaluronate and chrondroitin proteoglycans are coordinately deposited in SAM as cells begin spreading and movement over the substrate. Cells attaching to serum-coated or CIg coated substrates deposited SAM with identical compositions. The proteoglycan nature of the GAGs in SAM has been examined as well as the ability of proteoglycans to form two classes of reversibly dissociable “supramolecular complexes” - one class with heparan sulfate and glycopeptide-containing material and the second with hyaluronate-chondroitin complexes. Enzymatic digestion of “intact” SAM with trypsin or testicular hyaluronidase indicates that (1) only a small portion of long-term radiolabeled fibronectin and cytoskeletal protein is bound to the substrate via hyaluronate or chondroitin classes of GAG; (2) most of the fibronectin, cytoskeletal protein and heparan sulfate coordinately resist solubilization; and (3) newly synthesized fibronectin, which is metabolically labile in SAM, is linked to SAM by hyaluronate- and/or chondroitin-dependent binding. All of our studies indicate that heparan sulfate is a direct mediator of adhesion of cells to the substrate, possibly by binding to both cell-surface fibronectin and substrate-bound CIg in the serum coating; hyaluronate-chondroitin complexes in SAM appear to be most important in motility of cells by binding and labilizing fibronectin at the periphery of footpad adhesions, with subsequent cytoskeletal disorganization.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110314
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  • 114
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    Alkaline phosphatase of basal lateral and brush border plasma membranes from intestinal epithelium (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 451-466 
    Details
    ISSN: 0091-7419
    Keywords: alkaline phosphatase ; basal lateral membranes ; brush border membranes ; intestinal epithelium ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The alkaline phosphatases present on isolated brush border and basal lateral membranes of rat duodenal epitheilum were examined by means of a variety of biochemical assays and physical methods. The two alkaline phosphatases have similar pH optima of 9.6-9.8, similar substrate km's for p-nitrophenyl phosphate (PNPP) of 71 micromolar, similar responses to the inhibitors 2-mercaptoethanol, theophylline, phenylalanine, and ethylenediaminetetraacetic acid (EDTA), similar sensitivities to calcium, magnesium, zinc, sodium, and potassium, and similar insensitivities to digestion with trypsin or papain. The two enzymes also exhibit similar molecular weights on SDS-polyacrylamide gels in the range 124,000-150,000, and both enzymes show an Rf value of 0.092 on Triton X-100 polyacrylamide gels, indicating similar intrinsic charges. The Vmax of the brush border enzyme is ten times greater than that of the basal lateral enzyme, 140 μmoles/mg-h as opposed to 14 μmoles/mg-h. The differences in Vmax are a reflection of the known distribution of alkaline phosphatase in rat duodenum, there being more alkaline phosphatase activity present on the brush border than on the basal lateral surface. One other major difference was observed between the two enzymes, the stimulation of the basal lateral and not the brush border alkaline phosphatase by SDS, Triton X-100, or cholate. We conclude that the enzymes are very similar to one another and probably perform similar membrane functions.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110404
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  • 115
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    Selection of malignant melanoma variant cell lines for ovary colonization (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 517-528 
    Details
    ISSN: 0091-7419
    Keywords: cell variants ; electron microscopy ; malignant melanoma ; melanin ; metastasis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Murine melanoma line B16-F1, which shows some specificity for metastatic organ colonization of lung but rarely metastasizes to ovary, was used to select variant cell lines with increased preference for experimental ovary metastasis. Ovary-colonizing melanoma cell lines were sequentially selected in syngeneic C57BL/6 mice by repeated intravenous administration and surgical recovery of ovarian melanoma tumors for tissue culture. After ten selections for experimental ovary metastasis, line B16-010 was established which formed experimental metastatic ovary tumors in almost every test animal. In tissue culture B16-010 cells grew in circular in circular colonies with rounded, smooth cell peripheries compared to B16-F1 cells which were flatter, grew in irregular patterns, and exhibited long cellular projections. Ovary-selected B16 lines contained less melainin pigment (B16-010 〈 B16-05 〈 B16-01 ≅ B16-F1) compared to the parental melanoma line. Together with previous cloning and selection data, these results are consistent with the preexistence of highly malignant cells in the parental tumor population that possess the ability to metastasize to specific organs.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110410
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  • 116
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    Solubilization and conversion of hepatic adenylate cyclase to a form requiring MnATP as substrate (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 31-37 
    Details
    ISSN: 0091-7419
    Keywords: adenylate cyclase ; liver ; solubilized ; MnATP ; MgATP ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A general feature of membrane-bound adenylate cyclase systems is the “lability” of the basal enzyme to dispersion by detergents. A stable form of the detergentsolubilized enzyme is obtained only if the membrane-bound enzyme is first pretreated with fluoride or Gpp(NH)p. However, we have found with the basal hepatic enzyme that the lability is evident primarily when MgATP is used as substrate; substitution of MnATP for MgATP reveals that substantial basal activity survives detergent treatment. This effect is independent of the detergent; it is seen with either Lubrol PX or with deoxycholate. In addition to the altered substrate requirement, the membrane-bound and solubilized forms of the basal enzyme exhibit other differences. In contrast to the membrane-bound form, the solubilized enzyme shows (1) weak stimulation by Gpp(NH)p; (2) little inhibition by adenosine, (3) strong inhibition by Pi or PPi, and (4) and apparent loss of the Me2+-reactive regulatory site. Such dissimilarities between membranebound and solubilized cyclase are not seen if the membranes are pretreated with Gpp(NH)p prior to exposure to detergents. The characteristics of the solubilized basal hepatic enzyme are similar to those of the naturally occurring soluble adenylate cyclase found in mature rat testes. It would appear that separation of adenylate cyclase from components that confer regulation by divalent cation and guanine nucleotides produces a form of the enzyme that will turnover only MnATP; this may represent the free catalytic moiety. Such preparations could be useful in reconstructing some of the regulatory functions of adenylate cyclase seen in its membrane-bound form.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100104
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  • 117
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    Tight junction development between cultured hepatoma cells: Possible stages in assembly and enhancement with dexamethasone (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 13-30 
    Details
    ISSN: 0091-7419
    Keywords: hepatoma ; cell culture ; tight junctions ; gap junctions ; freeze-fracture ; dexamethasone ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Freeze-fracture and thin-section methods were used to study tight junction formation between confluent H4-II-E hepatoma cells that were plated in monolayer culture in media with and without dexamethasone, a synthetic glucocorticoid. Three presumptive stages in the genesis of tight junctions were suggested by these studies: (1) “formation zones” (smooth P-fracture face ridges deficient in intramembranous particles), apparently matched across a partially reduced extracellular space, develop between adjacent cells; (2) linear strands and aggregates of 9-11 nm particles collect along the ridges of the formation zones. The extracellular space was always reduced when these structures were found matched with pits in gentle E-face depressions; (3) the linear arrays of particles on the ridges associate within the membranes to form the fibrils characteristic of mature tight junctions. The formation zones resemble tight junctions in terms of size, complexity and the patterns of membrane ridges. Although some of the beaded particle specialization may actually be gap junctions, it is unlikely that all can be interpreted in this way. No other membrane structures were detected that could represent developmental stages of tight junctions. Dexamethasone (at 2 × 10-6 M) apparently stimulated formation of tight junctions. Treated cultures had a greater number of formation zones and mature tight junctions, although no differences in qualitative features of the junctions were noted.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100103
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    Differences in the redistribution of concanavalin A and wheat germ agglutinin binding sites on mouse neuroblastoma cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 61-77 
    Details
    ISSN: 0091-7419
    Keywords: lectins ; binding sites ; neuroblastoma cells ; receptor redistribution ; cell surface labeling ; cytochalasin B ; concanavalin A ; wheat germ agglutinin ; fluorescent microscopy ; scanning electron microscopy ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Concanavalin A (Con A), wheat germ agglutinin (WGA), and Ricinus communis agglutinin (RCA) bound with either 125I, fluorescent dyes, or fluorescent polymeric microspheres were used to quantitate and visualize the distribution of lectin binding sites on mouse neuroblastoma cells. As viewed by fluorescent light and scanning electron microscopy, over 107 binding sites for Con A, WGA, and RCA appeared to be distributed randomly over the surface of differentiated and undifferentiated cells. An energy-dependent redistribution of labeled sites into a central spot occurred when the cells were labeled with a saturating dose of fluorescent lectin and maintained at 37°C for 60 min. Reversible labeling using appropriate saccharide inhibitors indicated that the labeled sites had undergone endocytosis by the cell. A difference in the mode of redistribution of WGA or RCA and Con A binding sites was observed in double labeling experiments. When less than 10% of the WGA or RCA lectin binding sites were labeled, only these labeled sites appeared to be removed from the cell surface. In contrast, when less than 10% of the Con A sites were labeled, both labeled and unlabeled Con A binding sites were removed from the cell surface. Cytochalasin B uncoupled the coordinate redistribution of labeled and unlabeled Con A sites, suggesting the involvement of microfilaments. Finally, double labeling experiments employing fluorescein-tagged Con A and rhodamine-tagged WGA indicate that most Con A and WGA binding sites reside on different membrane components and redistribute independenty of each other.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100107
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    Activation of cyclic AMP-dependent protein kinase and stimulation of protein phosphorylation in response to adenosine in C-1300 murine neuroblastoma (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 125-135 
    Details
    ISSN: 0091-7419
    Keywords: protein phosphorylation ; cAMP-dependent protein kinases ; adenosine on cyclic AMP ; C1300 neuroblastoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: DEAE-cellulose chromatography of the 20,000g supernatant fraction of homogenates of C-1300 murine neuroblastoma (clone N2a) yields one major and two minor peaks of cyclic AMP-dependent protein kinase activity. Assessment of the endogenous activation state of the enzyme(s) reveals that the enzyme is fully activated by the treatment of whole cells with adenosine (10 μM) in the presence of the phosphodiesterase inhibitor Ro 20 1724 (0.7 mM). This treatment produces a large elevation in the cyclic AMP content of the cells. The treatment of whole cells with adenosine alone (1-100 μM) or Ro 20 1724 alone (0.1-0.7 mM) produces minimal elevations in cyclic AMP but nevertheless causes significant activations of cyclic AMP-dependent protein kinase. The autophosphorylation of whole homogenates of treated and untreated cells was studied using [γ-32P] ATP, sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Treatments which activate cyclic AMP-dependent protein kinase selectively stimulate the incorporation of 32P into several proteins. This stimulation is most prominent in the 15,000-dalton protein band. The addition of cyclic AMP to phosphorylation reactions containing homogenate of untreated cells stimulates the phosphorylation of the same protein bands. These results indicate that adenosine may have regulatory functions through its effect on the cyclic AMP: cyclic AMP-dependent protein kinase system.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100203
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    Relationship between steps in 8-anilino-1-naphthalene sulfonate (ANS) fluorescence and changes in the energized membrane state and in intracellular and extracellular adenosine 5′-triphosphate (ATP) levels following bacteriophage T5 infection of Escherichia coli (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 329-347 
    Details
    ISSN: 0091-7419
    Keywords: ANS fluorescence ; membrane hydration ; cholesterol ; phospholipid-cholesterol interaction ; infrared spectra ; red cell membranes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The addition of bacteriophage T5 to anaerobic, fermenting cells of Escherichia coli B or K-12 in the presence of 8-anilino-1-naphthalene sulfonate (ANS), N-phenylnaphthyl-1-amine (NPN), or dansyl ethylamine causes the fluorescence of these probes to rise in two steps, the first occurring immediately upon addition, the second delayed by 6 min. The conditions necessary for observing this phenomenon are defined (cell density, probe concentration, substrate, absence of an electron acceptor, multiplicity of infection, growth, and harvesting conditions).The magnitudes of the first and second steps in fluorescence are dependent upon the multiplicity of infection; the timing of the steps is not. The first step correlates with a breakdown in the potassium or rubidium permeability barrier of the cell, and it occurs either aerobically or anaerobically, with fermentable or nonfermentable substrates. The second step occurs only with cells that are without an available electron acceptor, are fermenting, and which have a functional membrane-bound, Ca2+-Mg2+-dependent adenosine triphosphatase (ATPase). The results are consistent with disturbance of energization of the cell membrane by the membrane-bound ATPase at the time of the second step in fluorescence. No change in the intracellular level of adenosine 5′-triphosphate (ATP) was seen, whereas the extracellular level increased sharply, starting 3-6 min after phage addition. The quantity of ATP found in the medium by 30 min after infection amounted to about four times the amount present inside the cells at the time of infection. The quantity and rate of efflux of ATP was similar under aerobic and anaerobic conditions.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100305
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    Characterization of antigenic sialoglycoprotein subunits of the placental brush border membranes: Comparison with liver and kidney membrane subunits by two-dimensional electrophoresis (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 287-305 
    Details
    ISSN: 0091-7419
    Keywords: antigenic membrane glycoproteins ; immunoprecipitation ; two-dimensional electrophoresis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The sialoglycoprotein subunits of human placental brush border membranes were labeled by sequential treatment with periodate and (3H)-sodium borohydride, which trititates sialic acid, and by lactoperoxidase-catalyzed (125I) iodination of tyrosine residues. The labeled subunits were characterized with respect to their affinity for antisera raised against Triton X-100 extracts of placental brush border membranes. The immunochemically reactive components were analyzed by two-dimensional electrophoresis according to a modification of the O'Farrell technique [20] enabling the assignment of estimated Mr̄ and pI. Of the 33 3H-labeled brush border subunits present in Triton X-100-solubilized membrane preparations, 18 subunits reacted with antiplacental brush border antisera insolubilized on CNBr-activated Sepharose or in immunoprecipitates. Fourteen of these tritiated subunits were also labeled with 125I, confirming that these are glycoproteins.The plasma membranes of normal human liver and microsomes from kidney were examined for the placental brush border glycoprotein subunits by reaction with insolubilized antiplacental brush border antisera and two-dimensional electrophoresis of the reacting tritium-labeled subunits. Comparison of the two-dimensional electrophoretic maps of the immunochemically reacting glycoproteins from liver, kidney, and placenta resulted in the identification of seven placental subunits in common with liver and kidney on the basis of antigenic cross-reactivity, Mr̄, and pI. Four placental glycoproteins were not found in the other tissues and are potentially specific to the placenta. Three of the placental subunits were only seen in placenta and kidney. Three of the subunits ran at the dye front and could not be assigned molecular weights. One of the subunits was poorly labeled by tritiation of sialic acid and was not considered.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100303
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    Carbohydrate structure of the major glycopeptide from human cold-insoluble globulin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 391-399 
    Details
    ISSN: 0091-7419
    Keywords: cold-insoluble globulin ; carbohydrate structure ; human plasma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cold-insoluble globulin (CIg) is a member of a group of circulating and cell-associated, high-molecular-weight glycoproteins termed fibronectins. CIg was isolated from human plasma by affinity chromatography on gelatin-Sepharose. SDS-polyacrylamide gel electrophoresis of the purified glycoprotein gave a double band that migrated near myosin. The CIg glycopeptides were released by pronase digestion and isolated by chromatography on Sephadex G-50. Affinity chromatography of the major G-50 peak on Con A-Sepharose resulted in two fractions: one-third of the glycopeptides were unbound and two-thirds were weakly bound (WB). Sugar composition analysis of the unbound glycopeptides by GLC of the trimethylsilyl methyl glycosides gave the following molar ratios: sialic acid, 2.5; galactose, 3.0; N-acetylglucosamine, 4.9; and mannose, 3.0. Sugar composition analysis of the WB glycopeptides gave the following molar ratios: sialic acid, 1.7; galactose, 2.0; N-acetylglucosamine, 4.1; and mannose, 3.0. The WB CIg glycopeptides cochromatographed on Sephadex G-50 with WB transferrin glycopeptides giving an estimated molecular weight of 2,800. After degradation with neuraminidase alone or sequentially with β-galactosidase the CIg and transferrin glycopeptides again cochromatographed. Methylation linkage analysis of the intact and the partially degraded glycopeptides indicated that the carbohydrate structure of the major human CIg glycopeptide resembles that of the major glycopeptide from transferrin.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110313
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    Isolation and immunological characterization of an iron-regulated, transformation-sensitive cell surface protein of normal rat kidney cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 371-390 
    Details
    ISSN: 0091-7419
    Keywords: viral transformation ; iron starvation ; membrane proteins ; procollagen ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have analyzed the surface proteins of cultured normal rat kidney (NRK) cells and virus-transfromed NRK cells subjected to iron deprivation. Such a treatment specifically induces two transformation-sensitive plasma membrane-associated glycoproteins with a subunit molecular wegiht of 160,000 (160 K) and 130,000 (130 K) daltons in NRK cells. In these cells the 160 K glycoprotein is readily available to lactoperoxidase-mediated iodination, and the 130 K is apparently inaccessible to iodination. Major differences were revealed when iodinated membrane proteins of normal and virus-transformed cells subjected to iron deprivation were compared. In Kirsten sarcoma virus-transformed NRK cells the 160 K glycoprotein was weakly labeled. In two clones of simian virus 40-transformed NRK cells the 160 K glycoprotein was weakly labeled or not at all. The 130 K glycoprotein was inaccessible to iodination in all the virus-transformed cell lines.The 160 K and 130 K glycoproteins were isolated form plasma membranes of NRK cells using preparative SDS gel electrophoresis. Antibodies generated against these glycoproteins stained the external surfaces of NRK cells and induced antigen redistribution. Evidence presented suggests that 160 K and 130 K are plasma membrane-associated procollagen molecules. A possible interaction of these proteins with transferrin is also described. The data suggest that these proteins may have an important role in the sequence of events leading to transformation.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110312
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    Subcellular fractionation of brown adipose tissue (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 445-449 
    Details
    ISSN: 0091-7419
    Keywords: subcellular fractionation ; brown adipose tissue ; plasma membranes ; microsomes ; Metrizamide ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The present study proposes a technique, using Metrizamide, which permits the preparation of brown adipose tissue plasma membranes from the crude mitochondria as well as from the crude microsome fraction. These plasma membranes have high relative specific activities of their marker enzyme, 5′-nucleotidase (15 ± 3 and 14 ± 2 respectively) and, particularly those originating in the crude microsomes, are relatively free of mitochondria contamination. This study also shows the influence of the mode of cell disruption on microsome integrity. When cell disruption was achieved by grinding in liquid nitrogen the purified microsome NADPH cytochrome c reductase specific activity was found to be 3.5 times greater than that of microsomes obtained after homogenization of the tissue.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/jss.400110403
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    Masthead (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979) 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400100101
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    A possible modulation of acetylcholine receptors of embryonic chick muscle cells by α-bungarotoxin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 39-50 
    Details
    ISSN: 0091-7419
    Keywords: muscle ; acetylcholine ; acetylcholine receptors ; α-Bungarotoxin ; chick ; modulation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Acetylcholine receptors were assayed with α-bugarotoxin on embryonic chick skeletal muscle growing in primary cell culture. Toxin was bound specifically to muscle cells and could be competed with D-tubocurarine. Two dissociation constants were obtained by equilibrium binding: 7.2 × 10-9M and 2.7 × 10-7M at 25°C. Two sets of rate constants were also obtained from dissociation kinetics. There are five times more low affinity sites on cells than high affinity sites. The average density of high-affinity receptors is about 200/μm2.A time course of toxin binding to receptors at 37°C vs 25°C in growth medium revealed that under conditions permitting growth and metabolism, toxin bound to cells was lost. The possibility that the growth medium was in-activating toxin molecules was ruled out by showing that unbound toxin molecules in the medium were fully capable of binding to fresh cultures.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100105
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    Requirement for guanosine triphosphate in the activation of adenylate cyclase by cholera toxin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 51-60 
    Details
    ISSN: 0091-7419
    Keywords: cholera toxin ; GTP ; pigeon erythrocyte ; adenylate cyclase ; cytosolic factor ; phosphodiesterase protein activator ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The activation of adenylate cyclase in lysed pigeon erythrocytes requires, among several cofactors, a nucleotide which may be ATP, GTP, or many other triphosphates. However, after removal of endogenous nucleotides by gel filtration or by adsorption onto charcoal the requirement can be met only by GTP, or an analog of GTP. The GTP is required during the activation of the cyclase by toxin even if GTP is also included during the subsequent adenylate cyclase assay, conducted without toxin. In the presence of GTP it is possible to assay for the cytosolic protein that is also required for the action of cholera toxin. By gel filtration, its apparent molecular weight is 15,000-20,000.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100106
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    Proteolytic cleavage and structural transformation: Their relationship in bacteriophage T4 capsid maturation (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 1-11 
    Details
    ISSN: 0091-7419
    Keywords: virus assembly ; limited proteolysis ; conformational change ; cooperativity ; electron microscopy ; optical diffraction ; computer image processing ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Giant T4 phage capsoids formed in canavanine-treated cultures infected by phage mutants in genes 21 and 17, respectively, differ with regard to cleavage of the major capsid protein, gp 23, and in the fine structure of their hexagonal surface lattices. Quantitative computer processing of electron micrographs shows that the significant differences in capsomer morphology amount to six symmetrically placed features present in the uncleaved hexamer but absent after cleavage. These features may be related with the N-terminal portions of gp 23 monomers excised by phage-specific proteolysis. Cleaved 17- giants can be induced to undergo a further structural transformation (expansion). Structural characteristics of partially transformed giant particles give clues about the dynamics of the cleavage and expansion transformations. Both processes appear to be polar, initiating in one cap and propagating along the particle. The transition zone of partial cleavage is diffuse, whereas the transition between unexpanded and expanded areas is confined to a narrow band of some 20 nm width.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100102
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    Masthead (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979) 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400100201
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    Growth factors and gangliosides: A possible new perspective in neuronal growth control (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 111-124 
    Details
    ISSN: 0091-7419
    Keywords: growth factors ; gangliosides ; neurogenesis ; cell developmental program ; neuronal cell lines ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: For many permanent cell lines the transition from a growing (P) to a resting (R) state is reversibly controlled by growth factors present in serum. This P-to-R transition was studied in a neuronal cell line (B 104) with respect to the action of serum, dibutyryl cyclic AMP (DBcAMP), gangliosides, and a glioma cell-produced growth factor GGF. In this cell system gangliosides seem to act as differentiation and survival factors. The kinetics of uptake of radioactively labeled gangliosides and survival experiments both support the idea of the stable incorporation of exogenously added gangliosides into the cells. Based on the experimental evidence a new model of cell development is proposed. Thus in addition to the R or G0 state, which in this cell system is rather unstable and probably regulated by cyclic nucleotides, we postulate a differentiated D state, which is controlled by gangliosides and which is characterized by its stability (survival time). This D compartment seems to be closer to the in vivo differentiated neuron than does the R or P state. The possible mechanisms for the action of gangliosides are discussed.
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    URL: http://dx.doi.org/10.1002/jss.400100202
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    Independence of the lethal actions of glucocorticoids on lymphoid cells from possible hormone effects on calcium uptake (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 165-174 
    Details
    ISSN: 0091-7419
    Keywords: glucocorticoids ; calcium ; thymus ; lymphosarcoma ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We have examined the possibility that hormone-induced increases in calcium uptake might initiate the lethal actions of glucocorticoids in two types of lymphoid cells. Hormone-induced increases in nuclear fragility are used as the measure of hormone action, since in both rat thymus cells and in mouse P1 798 lymphosarcoma cells increased nuclear fragility (the inability of nuclei to survive lysis of the cells by hypotonic shock) precedes other indices of cellular deterioration by several hours.In the case of the tumor cells, those from corticosteroid-sensitive lines are less able to withstand incubation in vitro than resistant cells. Such differences in cell survival are predicted both by earlier changes in nuclear fragility and also by differences in calcium uptake. However, there is no detectable early glucocorticoid effect on calcium uptake that precedes or coincides with the substantial hormone-induced increases in nuclear fragility that develop in the sensitive cells by 2 h.In rat thymus cells the absence of calcium in the medium does prevent some of the increase in nuclear fragility and cell disintegration that occurs spontaneously during incubation in vitro. Nevertheless, when cells are exposed to hormones the glucocorticoid effect on nuclear fragility develops in the absence of calcium and is similar in magnitude to that seen in the presence of calcium.We conclude that calcium seems to enhance the spontaneous deterioration of lymphoid cells, and there is a large increase in calcium uptake that occurs as cells deteriorate. It nevertheless seems unlikely that hormone-induced changes in calcium uptake initiate the lethal actions of glucocorticoids. The data also support a proposal made earlier [2] that resistance to glucocorticoids in tumor cells may develop by the selection of cells with hardier membranes.
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    URL: http://dx.doi.org/10.1002/jss.400100206
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    Effect of metabolic inhibitors on vasopressin-stimulated transport systems in the toad bladder (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 175-184 
    Details
    ISSN: 0091-7419
    Keywords: vasopressin ; nocodazole ; urea transport ; rotenone ; dinitrophenol ; methylene blue ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Vasopressin increases the permeability of receptor cells to water and, in tissues such as toad bladder, to solutes such as urea. While cyclic AMP appears to play a major role in mediating the effects of vasopressin, there is evidence that activation of the water permeability system and the urea permeability system involves separate pathways. In the present study, we have shown that inhibitors of oxidative metabolism (rotenone, dinitrophenol, and methylene blue) selectively inhibit either vasopressin-stimulated water flow or vasopressin-stimulated urea transport. There was no inhibition, however, when exogenous cyclic AMP was substituted for vasopressin, and little to no inhibition when the potent analogue 8-bromoadenosine 3′,5′-cyclic monophosphate (8-Br-cAMP) was employed. Rotenone had no effect on adenylate cyclase activity or cyclic AMP levels within the cell; dinitrophenol decreased adenylate cyclase activity minimally.Additional studies with vinblastine and nocodazole, inhibitors of microtubule assembly, demonstrated an inhibition of vasopressin and cyclic AMP-stimulated water flow but showed no effect on urea transport.We would conclude that water and urea transport, as examples of hormone-stimulated processes, have different links to cell metabolism, and that in addition to cyclic AMP, a non-nucleotide pathway may be involved in the action of vasopressin.
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    URL: http://dx.doi.org/10.1002/jss.400100207
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    Properties of (Mg2+ + Ca2+)-ATPase of erythrocyte membranes prepared by different procedures: Influence of Mg2+, Ca2+, ATP, and protein activator (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 215-225 
    Details
    ISSN: 0091-7419
    Keywords: (Mg2+ + Ca2+)-ATPase ; erythrocyte membranes ; endogenous protein activator ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Erythrocyte membranes prepared by three different procedures showed (Mg2+ + Ca2+)-ATPase activities differing in specific activity and in affinity for Ca2+. The (Mg2+ + Ca2+)-ATPase activity of the three preparations was stimulated to different extents by a Ca2+-dependent protein activator isolated from hemolystes. The Ca2+ affinity of the two most active preparations was decreased as the ATP concentration in the assay medium was increased. Lowering the ATP concentration from 2 mM to 2-200 μM or lowering the Mg:ATP ratio to less than one shifted the (Mg2+ + Ca2+)-ATPase activity in stepwise hemolysis membranes from mixed “high” and “low” affinity to a single high Ca2+ affinity. Membranes from which soluble proteins were extracted by EDTA (0.1 mM) in low ionic strengh, or membranes prepared by the EDTA (1-10 mM) procedure, did not undergo the shift in the Ca2+ affinity with changes in ATP and MgCl2 concentrations. The EDTA-wash membranes were only weakly activated by the protein activator. It is suggested that the differences in properties of the (Mg2+ + Ca2+)-ATPase prepared by these three procedures reflect differences determined in part by the degree of association of the membrane with a soluble protein activator and changes in the state of the enzyme to a less activatable form.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100211
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    Internalization and processing of the EGF receptor in the induction of DNA synthesis in cultured fibroblasts: The endocytic activation hypothesis (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 199-214 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The addition of EGF to cultured murine 3T3 cells produces a decrease in EGF binding activity with concomitant internalization and degradation of the initially bound EGF. When the EGF receptor on cultured 3T3 cells is affinity labeled with high specific activity 125I-EGF, and the fate of the affinity labeled EGF-receptor complex determined, the loss in binding activity was accounted for by receptor internalization and subsequent proteolytic processing of the EGF receptor molecules in the lysosomes. Studies of the effects of EGF concentration on EGF binding by cells, EGF-induced receptor internalization and EGF-induced stimulation of 3H-thymidine uptake into cellular DNA show that there is a direct correlation between EGF-induced receptor internalization and EGF-induced stimulation of DNA synthesis, but not between EGF binding and EGF-induced stimulation of DNA synthesis. This correlation is lost at high EGF concentrations, where stimulation of DNA synthesis is suboptimal. Optimal stimulation of DNA synthesis requires a minimum of 6 h of incubation of EGF with cells, and the suboptimal stimulation of DNA synthesis at high EGF concentration is intensified when the period of incubation of EGF with cells is less than 6 h. These data are consistent with a model of hormone signal transmission by Endocytic Activation, wherein the activation of EGF-induced processes requires constant EGF-induced internalization of receptor for a requisite 6-8 h period as an obligatory step in production of “second messenger” in the action of this hormone.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400100210
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    Selective protein transport: Characterization and solubilization of the phosvitin receptor from chicken oocytes (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 491-504 
    Details
    ISSN: 0091-7419
    Keywords: oocyte protein transport ; receptor solubilization ; phosvitin receptor ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Phosvitin (PV), a subunit of a female-specific protein, vitellogenin, binds to oocyte membranes with a KD of 10-6 M. Binding reaches equilibrium within 30 min after incubation at 25°C. Bound 125I-PV dissociates from the membrane with a t1/2 of 13 h when incubated in buffer. However, when 125I-PV-labeled membranes are incubated in buffer containing 10-5 M unlabeled PV, 50% of the initially bound 125I-PV dissociates from the membrane within 10 min. These results support the conclusion that PV binds to a membrane-associated receptor.Solubilization studies show that Triton X-100 solubilizes up to 45% of the total membrane-bound 125I-PV. Gel-exculsion chromatography of the solubilized material yields a 500,000 dalton 125I-PV-containing complex separated from free 125I-PV. The 500,000 dalton complex completely dissociates to yield free 125I-PV when incubated with excess unlabeled PV. However, when incubated with (1) no addition, (2) IgG, or (3) serum albumin, the extent of dissociation is significantly reduced and is consistent with that which would be predicted on the basis of the observed dissociation rate in the absence of unlabeled PV.These results suggest that bound 125I-PV can only be displaced by unlabeled PV. These results also indicate that the 500,000 dalton species is a solubilized PV-receptor complex and that it is possible to solubilize the PV-receptor in an active form.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120409
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  • 136
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    Tumor cell surfaces and malignancy (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 161-231 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120506
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  • 137
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    T and B lymphocytes: Recognition and function (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 233-332 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120507
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  • 138
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    Structure of the dna binding cleft of the gene 5 protein from bacteriophage fd (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 10 (1979), S. 457-465 
    Details
    ISSN: 0091-7419
    Keywords: DNA binding protein ; gene 5 ; fd bacteriophage ; X-ray diffraction ; protein-nucleic acid interactions ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The structure of the gene 5 DNA unwinding protein from bacteriophage fd has been solved to 2.3-Å resolution by X-ray diffraction techniques. The molecule contains an extensive cleft region that we have identified as the DNA binding site on the basis of the residues that comprise its surface. The interior of the groove has a rather large number of basic amino acid residues that serve to draw the polynucleotide backbone into the cleft. Arrayed along the external edges of the groove are a number of aromatic amino acid side groups that are in position to stack upon the bases of the DNA and fix it in place. The structure and binding mechanism as we visualize it appear to be fully consistent with evidence provided by physical-chemical studies of the protein in solution.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400100408
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  • 139
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    Structural and functional alterations in the surface of vascular endothelial cells associated with the formation of a confluent cell monolayer and with the withdrawal of fibroblast growth factor (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 73-114 
    Details
    ISSN: 0091-7419
    Keywords: fibronectin ; CSP-60 ; extracellular matrix ; thrombogenic properties ; low-density lipoprotein ; receptor redistribution ; asymmetry of cell surfaces ; cell morphology ; spatial configuration ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Vascular endothelial cells cultured in the presence of fibroblast growth factor (FGF) devide actively when seeded at low or clonal cell densities and upon reachin confluence adopt a morphologic appearance and differentiated properties similar to those of the vascular endothelium in vovi. In this review, we present some of our recent observations regarding the characteristics (both structural and functional) of these endothelial cells and the role of FGF in controlling their proliferation and normal differentation. At confluence the endothelial cells from a monolayer of closely apposed and nondividing cell that have a nonthrombogenic apical surface and can no longer internalize bound ligands such as low-density lipoprotein (LDL). The adoption of these properties is correlated and possibly causally related to changes in the cell surface such as the appearance of a 60,000 molecular weight protein (CSP-60); the disappearance of fibronectin from the apical cell surface and its concomitant accumulation in the basal lamina; and a restriction of the lateral mobility of various cell surface receptor sites. In contrast, endothelial cells that are maintained in the absence of FGF undergo within three passages alterations that are incompatible with their in vivo morphologic apperarance and physiologic beharior. They grow at confluence on top of each other and hence can no longer adopt both the structural (CSP-60, cell surface polarity) and functional (barrier function, nonthrombogenicity) attributes of differentiated endothelial cell. Since these characteristics can be reacquired in response to readdition of FGF, in addition to being a mitogen FGF may also be involved in controlling the differentitation and phenotypic expression of the vascular endothelium.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120108
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  • 140
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    Biosynthesis of membrane glycoproteins in rat hepatoma tissue culture cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 151-164 
    Details
    ISSN: 0091-7419
    Keywords: membrane glycoproteins ; posttranslational modifications ; intracellular transport ; secretion ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The early steps in the biosynthesis of glycoproteins associated with the plasma membranes of rat hepatoma tissue culture cells has been analyzed. By measuring the effect of tunicamycin on the incorporation of [3H] mannose and [3H] fucose into cell glycoproteins, it was determined that an interval of about 1 h was required to transfer the glycoprotein from the site of mannosylation to the site of fucosylation. This result was corroborated by an analysis of the time required for the appearance of either mannose or fucose-labeled glycoproteins at the cell surface. The separation of membrane glycoproteins by a two-dimensional gel system allowed the visualization of the modifications leading to both size and charge heterogeneity of these proteins. By following the changes in electrophoretic mobility introduced into membrane glycoproteins during a chase period after a pulse labeling, the time course of these molecular alterations could be estimated. Several glycoproteins have apparently higher rates of synthesis than the bulk of membrane-associated glycoproteins. Most of these glycoproteins were released within 2 h after biosynthesis from the intracellular membrane fraction and appear after 3 h in the medium. In addition to the glycoproteins that contain both mannose and fucose and that show a high degree of charge heterogeneity, there are other membrane-bound species that are not noticeably modified by the in corporation of fucose or sialic acids. These glycoproteins could represent constituents limited to the internal membrane system of the HTC cell.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120202
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  • 141
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    Biosynthesis and maturation of cellular membrane glycoproteins (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 209-226 
    Details
    ISSN: 0091-7419
    Keywords: membrane glycoproteins ; human diploid fibroblasts ; BHK21 cells ; exoglycosidases and endoglycosidases ; asparaginyl-oligosaccharides ; gel filtration ; processing of oligomannosyl core ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The biosynthesis and the processing of asparagine-linked oligosaccharides of cellular membrane glycoproteins were examined in monolayer cultures of BHK21 cells and human diploid fibroblasts after pulse-and pulse-chase labeling with [2-3H] mannose. After pronase digestion, radiolabeled glycopeptides were characterized by high-resolution gel filtration, with or without additional digestion with various exoglycosidases and endoglycosidases. Pulse-labeled glycoproteins contained a relatively homogenous population of neutral oligosaccharides (major species: Man9GlcNAc2ASN). The vast majority of these asparagine-linked oligosaccharides was smaller than the major fraction of lipid-linked oligosaccharides from the cell and was apparently devoid of terminal glucose. After pulse-chase or long labeling periods, a significant fraction of the large oligomannosyl cores was processed by removal of mannose units and addition of branch sugars (NeuNAc-Gal-GlcNAc), resulting in complex acidic structures containing three and possibly five mannoses. In addition, some of the large oligomannosyl cores were processed by the removal of only several mannoses, resulting in a mixture of neutral structures with 5-9 mannoses. This oligomannosyl core heterogeneity in both neutral and acidic oligosaccharides linked to asparagine in cellular membrane glycoproteins was analogous to the heterogeneity reported for the oligosaccharides of avian RNA tumor virus glycoproteins (Hunt LA, Wright SE, Etchison JR, Summers DF: J Virol 29:336, 1979).
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120207
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  • 142
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    Masthead (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979) 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120301
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  • 143
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    Gliding mycoplasmas are inhibited by cytochalasin B and contain a polymerizable protein fraction (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 299-304 
    Details
    ISSN: 0091-7419
    Keywords: mycoplasma ; cytochalasin B ; actin-like protein ; cytoskeleton ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Studies are presented on the effect of cytochalasin B (CB) on the growth of five Mycoplasma species, three Acholeplasma species, and one Spiroplasma species. The three gliding mycoplasma species (M) gallisepticum, M pneumoniae and M pulmonis are the only mycoplasmas inhibited by CB. These are the only prolaryotes reported to be inhibited by CB. This suggested that these three mycoplasmas might have some sort of cytoskeletal structure. A protein fraction has been isolated from M gallisepticum which polymerizes in 0.6 M KC1 and depolymerizes when KC1 is removed. This fraction contains a major 58,000-dalton protein, a 46,000-dalton protein, and a minor 87,000-dalton protein.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120303
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  • 144
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    Ganglioside patterns of metastatic and non-metastatic transplantable hepatocellular carcinomas of the rat (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 485-492 
    Details
    ISSN: 0091-7419
    Keywords: carcinoma ; cell surface ; ganglioside ; hepatoma ; metastatis ; sialic acid ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In previous investigations, we correlated levels of sialic acid, gangliosides, and ganglioside glycosyltransferases with tumorigenesis over a 24-week continuum of growth of hepatocellular neoplasms of the rat induced by the carcinogen N-2-fluorenylacetamide. However, metastatic tumors developed only rarely and were not analyzed. To investigate surface changes associated with metastasis, well-differentiated and poorly differentiated hepatocellular carcinomas were transplanted to syngeneic recipient rats. From those, several metastatic and nonmetastatic isolates were obtained and compared. Both total and ganglioside sialic acid amounts in transplantable hepatomas were elevated above control liver values but were significantly lower for metastatic lines than for nonmetastatic lines. The nonmetastatic lines were characterized by ganglioside patterns depleted in the precursor ganglioside GM3 (sialic acid-galactose-glucose-ceramide) and elevated in the products of the monosialoganglioside pathway. In contrast, metastatic isolates exhibited a restoration of GM3 and nearer normal amounts of other gangliosides. The findings point to differences in sialic acid-containing glycolipids, comparing metastatic and nonmetastatic hepatocellular carcinomas, and further extend the concept that ganglioside alterations do not cause tumorigenesis but are the end result of a cascade of events which apparently continue beyond the onset of metastasis.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110407
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  • 145
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    Isolation of cholera toxin receptors from a mouse fibroblast and lymphoid cell line by immune precipitation (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 273-291 
    Details
    ISSN: 0091-7419
    Keywords: cholera toxin-receptors ; cell growth ; glycolipids-transformation ; organization in membranes ; glycolipids as cell surface receptors ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Cholera toxin receptors have been isolated from both a mouse fibroblast (Balbc/3T3) and mouse lymphoid cell line labeled by the galactose oxidase borotritiide technique. Tritiated receptor-toxin complexes solubilized in NP40 were isolated by addition of toxin antibody followed by a protein A-containing strain of Staphylococcus aureus. In both cell types by far the major species of toxin receptor isolated was ganglioside in nature, although galactoproteins were also present in the immune complexes. Whether the galactoproteins form part of a toxin-receptor complex or are artifacts of the isolation procedure is presently unclear.The relative specificity of cholera toxin for a carbohydrate sequence in a glycolipid suggests that the toxin might prove a useful tool in establishing the function and organization of glycolipids in membranes. For example, interaction of cholera toxin with the mouse lymphoid cell line was shown to result in patching and capping of bound toxin, raising the possibility that the glycolipid receptor interacts indirectly with cytoskeletal elements. Cholera toxin might also be used to select for mutant fibroblasts lacking the toxin receptor and therefore having an altered glycolipid profile. Such mutants might prove useful in establishing the relationship (if any) between modified glycolipid pattern and other aspects of the transformed phenotype. Attempts to isolate mutants, based on the expectation that growth of cells containing the toxin receptor would be inhibited by the increase in cAMP levels normally induced by cholera toxin, proved unsuccessful. Cholera toxin failed to inhibit significantly the growth of either Balbc or Swiss 3T3 mouse fibroblasts although it markedly elevated cAMP levels.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120211
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  • 146
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    Comparison of the structures of human fibronectin and plasma cold-insoluble globulin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 505-516 
    Details
    ISSN: 0091-7419
    Keywords: fibronectin ; cold-insoluble globulin ; carbohydrate content ; proteoglycan ; proteolytic cleavage ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Human amniotic fluid fibronectin and plasma fibronectin (cold-incoluble globulin) are indistinguishable both immunologically and by amino acid composition. Cyanogen bromide and tryptic peptides also suggest substantial structural homology. However, carbohydrate analysis has demonstrated additional saccharides in fibronectin and an overall increase in carbohydrate content relative to coldinsoluble globulin. Furthermore, limited proteolytic cleavage of the two proteins indicates differences in primary structure or in conformation. Using affinity-purified antibodies to cold-insoluble globulin, a glucosamine-labeled pronaseresistant component, probably proteoglycan, was found to coprecipitate with fibronectin, suggesting an association between these two macromolecules in the connective tissue matrix.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120410
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  • 147
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    Electronic Resource
    Hormone-induced modification of EGF receptor proteolysis in the induction of EGF action (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 517-531 
    Details
    ISSN: 0091-7419
    Keywords: direct labeling of EGF receptors ; transient down-regulation of EGF receptors ; platelet derived growth factor ; receptor proteolysis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A proposal that EGF action is mediated through enhanced internalization of EGF receptors is modified to account for more recent evidence. EGF receptors turn over at a rapid rate, and the maintenance of a steady state of EGF receptors on the cell surface is provided through a rapid synthesis of EGF receptors, balancing their removal. This rapid turnover of unoccupied receptors may arise through their removal. This rapid turnover of unoccupied receptors may arise through their internalization and proteolysis in the lysosomes, in much the same way as receptors are internalized and degraded when exposed to EGF, which enhances internalization. This provides a dilemma for the endocytic activation concept, since slight enhancement of receptor internalization gives rise to a strong hormone response. This problem may be solved by the observation that EGF induces a change in its receptor, exposing an otherwise unavailable site for proteolytic cleavage. This hormone-dependent modification of receptors may be the critical step in the induction of responses to EGF and other hormones that are internalized with their receptors. Both platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) are shown to down-regulate EGF receptors, though transiently, placing still more stringent requirements on the specificity by which hormones might act through endocytic activation of their receptors.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120411
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  • 148
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    Eucaryotic gene regulation (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 31-78 
    Details
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120503
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