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  • 1985-1989
  • 1975-1979  (148)
  • 1965-1969
  • 1979  (148)
  • Molecular Cell Biology  (148)
  • 101
    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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  • 102
    Electronic Resource
    Electronic Resource
    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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  • 103
    Electronic Resource
    Electronic Resource
    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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  • 104
    Electronic Resource
    Electronic Resource
    Pyrenesulfonyl azide as a fluorescent label for the study of protein-lipid boundaries of acetylcholine receptors in membranes (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 327-338 
    Details
    ISSN: 0091-7419
    Keywords: AcChR-enriched membranes ; pyrenesulfonyl azide ; fluorescent probes ; photolabeling ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Acetylcholine receptor (AcChR) enriched membrane fragments from Torpedo californica electroplax were labeled by in situ photogenerated nitrenes from a hydrophobic fluorescent probe, pyrene-1-sulfonyl azide. Preferential photolabeling of membrane proteins, mainly AcChR, has been achieved and there is a pronounced exposure of the 48,000 and 55,000 molecular weight subunits of AcChR to the lipid environment of the membrane core.Covalent attachment of the photogenerated fluorescence probe does not perturb the α-neurotoxins' binding properties of membrane-bound AcChR or the desensitization kinetics induced by prolonged exposures to cholinergic agonists. Non-covalent photoproducts can be conveniently removed from labeled membrane preparations by exchange into lipid vesicles prepared from electroplax membrane lipids. Fluorescence features of model pyrene sulfonyl amide derivatives, such as fine vibrational structure of emission spectra or fluorescence lifetimes, are highly sensitive to the solvent milieu. The covalently bound probe shows similar fluorescence properties in situ. PySA photoproducts have great potential to spectroscopically monitor neurotransmitter induced events on selected AcChR subunits exposed to the hydrophobic environment of membranes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110308
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  • 105
    Electronic Resource
    Electronic Resource
    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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  • 106
    Electronic Resource
    Electronic Resource
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110404
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  • 107
    Electronic Resource
    Electronic Resource
    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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  • 108
    Electronic Resource
    Electronic Resource
    Human placental cell surface antigens: Expression by cultured cells of diverse phenotypic origin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 503-515 
    Details
    ISSN: 0091-7419
    Keywords: glycoproteins ; two-dimensional electrophoresis ; differentiation ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The present work examined the expression of cell surface glycoprotein antigens in cultured human cell lines. The set of glycoproteins studied was defined by their immunoreactivity with antiserum developed to Triton-solubilized extracts of placental brush border membranes. Studies were performed using cell lines of trophoblastic (BeWo, JEG-3) and nontrophoblastic (Chang liver cells) origin, as well as diploid fibroblast cell lines (WI-38, GM-38).Antiplacental brush border antiserum reacts with at least 19 distinct antigens present in placental membrane preparations, each of which can be resolved and identified in two-dimensional electrophoresis. The subunit molecular weight and isoelectric point for all components were defined by their positions in the two-dimensional matrix. Thirteen of these could be detected among the five cell lines examined by lactoperoxidase-catalyzed cell surface iodination. One of these 13 antigens has been identified as the placental isoenzyme of alkaline phosphatase (PAP). The expression of this component is limited to choriocarcinonia cells and Chang liver cells and it is not present in diploid fibroblasts. Under normal circumstances expression of PAP is unique to the differentiated placenta but has been frequently demonstrated in both trophoblastic and nontrophoblastic neoplasms.Two other antigens are variably expressed among the different cell types examined in the present study and their presence or absence was independent of the trophoblastic, epithelial nontrophoblastic, or fibroblastic origin of the cells.Ten surface antigens were expressed in all five cell lines. Six of these had previously been found common to membranes from three adult differentiated tissues, including liver and kidney, as well as placenta (Wada et al, J Supramol Struc 10(3):287-305, 1979). The presence of this set of antigens in cultured cells as well extends the possibility that these are ubiquitously expressed on human cell surfaces. Two other antigens observed in all cultured cells had been found in both placental and either kidney or liver membranes and may represent common functions shared by many tissues which are also necessary for growth in vitro. The two remaining placental antigens seen in all cultured cells have previously been shown to be absent in adult tissues. Their presence in cultured cells but not in the membranes of resting differentiated tissues may signify the expression of glycoproteins characteristic of trophoblasts in all cells adapted to growth in culture.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110409
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  • 109
    Electronic Resource
    Electronic Resource
    Modulation of cell surface iron transferrin receptors by cellular density and state of activation (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 579-586 
    Details
    ISSN: 0091-7419
    Keywords: growth factors ; transferrin receptors ; mitogenesis ; mixed lymphocyte culture ; cell cycle ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: This report describes investigations of plasma membrane transferrin receptors on a variety of lymphoid cell lines and normal peripheral blood lymphocytes during activation and cell growth cycles. Transformed lymphoid cell lines have as many as 1,000 times the number of receptors found on normal resting lymphocytes. The number of iron transferrin receptors on continuous cell lines as well as normal human fibroblasts is down-regulated during the transition from log-phase growth to stationary plateau growth. When normal lymphocytes are transformed by mixed lymphocyte culture or mitogens, they rapidly express a 50-fold increase in the number of transferrin binding sites. This appearance of iron transferrin receptors anticipates nuclear changes during cell activation and subsequent mitosis of normal cells.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110415
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  • 110
    Electronic Resource
    Electronic Resource
    Structural states of dictyostelium myosin (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 1-14 
    Details
    ISSN: 0091-7419
    Keywords: myosin ; Dictyostelium ; RNA ; motility ; nonmuscle cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Myosin purified from Dictyostelium amoebae has approximately 10% by weight of RNA associated with it, unless specific steps (DEAE cellulose chromatography or R Nase digestion) are taken to remove it. This RNA has significant effects on the structural states formed by the myosin at low ionic strength in the presence of Mg2+.Rapid precipitation of Rna-free myosin by dilution generates bipolar thick filaments (540 nm long, 33 nm thick), often with a bare zone and a 15-nm transverse repeat. Rapid precipitation of myosin with copurified RNA yields linear aggregates of bipolar filaments, showing some lateral association.Slow precipitation of RNA-free myosin by dialysis yields very long filaments or ribbons (〉5 μm, 30-60 nm wide) in which the myosin may be packed diagonally across the filament, similar to the “side-polar” aggregates formed by other nonmuscle myosins and by smooth muscle myosin (Craig R, Megerman J: J Cell Biol 75:990, 1977; Hinssen H, D'Haese J, Small JV, Sobieszek A: J Ultrastruct Res 64:282, 1978). Slow precipitation of myosin with copurified RNA generates linear filaments with repeat intervals of 290 and 650 nm.Other polyanions were tested for their effects on myosin aggregation. Total RNA and ribosomal RNA from Dictyostelium, when added to RNA-free myosin, also induced the extensive linear aggregation seen with the copurified RNA/myosin complex, although higher concentrations of RNA were required to obtain quantitatively the same effect. DNA and heparin were also effective inducers of linear aggregation, whereas homopolymers of nucleotides and of acidic or basic amino acids were poorly effective.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120102
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  • 111
    Electronic Resource
    Electronic Resource
    Possible role of fibronectin in malignancy (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 139-150 
    Details
    ISSN: 0091-7419
    Keywords: fibronectin ; tumor ; malignancy ; cell shape ; hormone ; embryogenesis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Frozen sections of tumors induced by injecting virally transformed cells into animals were stained for fibronectin by immunofluorescence. Many tumor cell lines do not express fibronectin in tumors in situ even though some of them express fibronection in culture. Cell shape and hormones appear to influence the expression of fibronectin in culture; however, it is nuclear how fibronection expression is regulated in vivo.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120111
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  • 112
    Electronic Resource
    Electronic Resource
    Evidence of microfilament-associated mitochondrial movement (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 165-175 
    Details
    ISSN: 0091-7419
    Keywords: microvilli ; Malpighian tubule ; cytoskeleton ; actin ; cell motility ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The mitochondria in the lower Malpighian tubule of the insect Rhodnius prolixus can be stimulated by feeding in vivo and by 5-hydroxytryptamine in vitro, to move from a position below the cell cortex to one inside the apical microvilli. During and following their movement into the microvilli, the mitochondria are intimately associated with the microfilaments of the cell cortex and microvillar core bundle. Bridges approximately 14 nm in length and 4 nm in diameter are observed connecting the microvillar microfilaments to the outer mitochondrial membrane and microvillar plasma membrane. Depolymerization of all visible microtubules with colchicine does not inhibit 5-HT-stimulated mitochondrial movement. On the other hand, treatment with cytochalasin B does block mitochondrial movement, suggesting that microfilaments play a role in the mitochondrial motility. We have labeled the microvillar microfilaments, which are 6 nm in diameter, with heavy meromyosin, which supports the contention that they contain actin. A model of the mechanism of mitochondrial movement is presented in which mitochondria slide into position in the microvilli along actin-containing microfilaments in a manner analogous to the sliding actin-myosin model of skeletal muscle.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120203
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  • 113
    Electronic Resource
    Electronic Resource
    Introduction of metastatic heterogeneity by short-term in vivo passage of a cloned transformed cell line (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 227-243 
    Details
    ISSN: 0091-7419
    Keywords: cloned hepatic cell line ; isolation of metastatic variants ; metastatic heterogeneity introduced by ascites passage ; metastatic homogeneity and stability ; quantitative lung colony assay ; scanning electron microscopy ; tumor cell arrest and survival ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: An experimental system for the study of metastasis has been developed using an epithelioid cell line of hepatic origin which had previously been chemically transformed in vitro. These metastatic cells were studied in the syngeneic rat strain. The cloned parent cell line metastasizes only to the lungs following in travenous, subcutaneous, or intraperitoneal injection. The metastatic phenotype is stable during in vitro passage, and subclones from the parent clone have a metastatic capacity statistically similar to that of the parent clone. Following ascites passage of the parent cell line, the cell population obtained exhibits the same metastatic ability as the parent clone. However, subclones obtained from the ascites-passaged population exhibit metastatic heterogneity. This heterogeneity is introduced by the host passage and not by in vitro culture or subcloning. In the case of the two metastatic variants examined, the difference in the metastatic phenotype is found not to be due to differences in arrest or trapping of the cells but appears to be related to long-term survival and proliferation of the tumor cells following their arrest in the lungs. Morphologically the variants are very similar, and growth of the metastatic foci provokes a vigorous inflammatory response by the host.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400120208
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  • 114
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    Electronic Resource
    Scanning electron microscopy of differentiated liver cells transformed in vitro by chemical carcinogens (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 293-298 
    Details
    ISSN: 0091-7419
    Keywords: SEM ; chemical carcinogenesis in vitro ; epithelial liver cell cultures ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A scanning electron microscopy study was carried out on differentiated liver cells transformed in vitro by three chemical carcinogens into cells that give rise to carcinomas. The results indicate that the transformed cells grow as a rule in tightly adherent monolayers but differ in topography. There is a tendency toward heterogeneity in cell shape compared to the normal and on the whole toward a larger number of surface microvilli in the malignant cell population. However, both in sparse and confluent cultures the topographic differences are often not striking enough to unequivocally distinguish single neoplastic cells from the normal.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400120302
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  • 115
    Electronic Resource
    Electronic Resource
    β-Bungarotoxin binding sites (acetylcholine receptors) in denervated mammalian sarcolemma (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 321-334 
    Details
    ISSN: 0091-7419
    Keywords: denervated sarcolemma ; nonsynaptic acetylcholine receptors ; 125I-α-bungarotoxin ; ferritin-α-bungarotoxin ; electron microscopy ; freeze-fracture ; freeze-etching ; autoradiography ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The nonsynaptic sarcolemma of denervated skeletal muscle of rat shows an abundance of ∼15 nm intramembranous particles on the P face. These particles are either singly distributed or are in clusters, and they are essentially lacking from the comparable freeze-fractures of the innervated sarcolemma. Autoradiographic studies using 125I-α-bungarotoxin (BGT) on 1 μ-thick sections, and freeze-etch studies using ferritin-α-BGT conjugates on membrane fractions, show that the distribution of the label corresponds to the distribution of the 15-nm particles in the nonsynaptic sarcolemma. On the basis of these results and existing physiologic and biochemical data, it is suggested that the 15-nm intramembranous particles are components of the α-BGT binding sites, ie, acetylcholine (Ach) receptors, in the nonsynaptic sarcolemma of denervated muscle and that the two types of distributions represent two spatial manifestations of Ach receptor molecules. The significance of these findings in relation to synapse formation in denervated muscle is discussed.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400120305
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  • 116
    Electronic Resource
    Electronic Resource
    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.400120401
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  • 117
    Electronic Resource
    Electronic Resource
    Sequence of the amino-terminal region of rat liver ribosomal proteins S4, S6, S8, L6, L7a, L18, L27, L30, L37, L37a, and L39 (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 425-433 
    Details
    ISSN: 0091-7419
    Keywords: rat liver ribosomal proteins ; amino-terminus ; yeast ribosomes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The sequence of the amino-terminal region of eleven rat liver ribosomal proteins-S4, S6, S8, L7a, L18, L27, L30, L37a, and L39 - was determined. The analysis confirmed the homogeneity of the proteins and suggests that they are unique, since no extensive common sequences were found. The N-terminal regions of the rat liver proteins were compared with amino acid sequences in Saccharomyces cerevisiae and in Escherichia coli ribosomal proteins. It seems likely that the proteins L37 from rat liver and Y55 from yeast ribosomes are homologous. It is possible that rat liver L7a or L37a or both are related to S cerevisiae Y44, although the similar sequences are at the amino-terminus of the rat liver proteins and in an internal region of Y44. A number of similarities in the sequences of rat liver and E coli ribosomal proteins have been found; however, it is not yet possible to say whether they connote a common ancestry.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120403
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  • 118
    Electronic Resource
    Electronic Resource
    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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    Detection of erythrocyte membrane structural abnormalities in lecithin: Cholesterol acyltransferase deficiency using a spin label approach (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 1-7 
    Details
    ISSN: 0091-7419
    Keywords: erythrocyte membranes ; LCAT deficiency ; electron spin resonance ; spin label ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The membrane fluidity of erythrocytes from patients with Lecithin: cholesterol acyltransferase (LCT) deficiency was studied by means of electron spin resonance. The temperature dependence of the separation of the outer extrema of the spectra of 2-(3-carboxy-propyl)-4,4-dimethyl, 2-tridecyl-3-oxazolidinyloxyl spin probe was monitored for normal, presumed carrier and clinically affected subjects. The temperature profile of controls was significantly different form that of the presumed carriers and the clinically affected individuals. The results show that the compositional abnormalities previously noted in erythrocyte membranes from patients with LCAT deficiency are associated with alterations in the physicochemical state of the membrane. An investigation of the spectral lineshapes below 10°C allowed a distinction to be made at the membarne level between clinically affected subjects and clinically normal heterozygous carriers. Alterations in the temperature dependence of electron spin resonance parameters may provide a sensitive index of red cell membrane alterations in pathological states of generalized membrane involvement.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110102
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    Flow cytometry analysis of early DNA content changes in human and monkey cells following infection with simian virus 40 (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 25-31 
    Details
    ISSN: 0091-7419
    Keywords: simian virus 40 ; flow cytometry ; DNA synthesis induction ; transformation ; human diploid cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Simian virus 40 (SV40) is capable of inducing cellular DNA synthesis in permissive and nonpermissive cells. Utilizing flow cytometry, we analyzed the DNA content changes in two diploid human cell strains and two monkey cell lines. The osteogenesis imperfects (OI) human skin fibroblasts were induced into DNA synthesis, and within one to two cell generations, a polyploid cell population was produced. With WI-38 phase II cells, a similar pattern of increased cycling of cells into DNA synthesis was observed; however, the majority (∼60%) of the cells were blocked in the G2 + M phase of the cell cycle. At later time intervals, an increase in the G1 population was demonstrated. The two monkey cell lines responded to SV40 virus with an accumulation of cells in the G2 + M phase of the cell cycle. Thus, two diploid human cell strains exhibited different cell cycle kinetics early after infection with SV40 virus. The one strain (WI-38) behaved similarly to the two monkey cell lines studied. The other strain (OI) responded similarly to nonpermissive (transformin) cells infected with SV40 virus.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110104
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    Endogenous cyclic AMP does not modulate transport of hexoses, nucleosides, or nucleobases in chinese hamster ovary cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 51-60 
    Details
    ISSN: 0091-7419
    Keywords: cyclic AMP ; transport of nucleosides ; nucleobases ; hexoses ; Chinese hamster ovary cells ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In a previous study we have demonstrated that neither extracellular nor intracellular cyclic adenosine monophosphate (AMP) levels directly affect the uptake of nucleosides, nucleobases, or hexoses by various types of cultured mammalian cells. Uptake of these nutrients into cells, however, involves two processes operating in tandem: facilitated transport across the membrane and intracellular phosphorylation; and uptake rates generally reflect the rates of substrate phosphorylation rather than of transport. In the present study we have examined the question of whether substrate transport per se is regulated by intracellular cyclic AMP. Initially various cell lines, grown both in suspension and monolayer culture, were screened for their cyclic AMP response to prostaglandin E1, isoproterenol, and inhibitors of cyclic AMP phosphodiesterase. Prostaglandin E1 treatment of Chinese hamster ovary cells was selected as the systems giving the largest and most consistent (50-fold to 100-fold) elevation of cyclic AMP. Rapid kinetic techniques were used to measure the transport of 3-O-methylglucose, thymidine, adenosine, hypoxanthine, and adenine in wild-type cells and in mutant sublines incapable of phosphorylating these substrates. In no case was an increse in intracellular cyclic AMP accompanied by a singinficant change in the rate of transport of these substrates, although prostaglandin E1 slightly inhibited the transport of various substrates.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110106
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    Extracellular lectin and its glycosaminoglycan inhibitor in chick muscle cultures (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 61-67 
    Details
    ISSN: 0091-7419
    Keywords: lectin ; glycosaminoglycan ; extracellular material ; cell matrix ; cellular interactions ; myoblast development ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Embryonic chick muscle contains two developmentally regulated lectins, which may be involved in cell interactions. These endogenous lectins are assayed as agglutinins of appropriate test erythrocytes. One of these, called lectin-2, interacts with specific glycosaminoglycans, especially heparin and dermatan sulfate. Lectin-2 is present at constant levels in both chick fibroblast and chick muscle cells throughout 14 days of culture but is released into the medium of cultured embryonic muscle after 7-8 days of culture, soon after myoblast fusion. Lectin-2 interacts strongly with a component of substrate-attached material in embryonic muscle cultures which is extractable from the culture dishes with alkali after the cells have been removed with ethylediaminetetraacetic acid. The active component in the substrate-attached material appears to be a glycosaminoglycan that is a more potent inhibitor of lectin-2 agglutination activity than any of the known glycosaminoglycans that we have tested. The active material is degraded by chondroitinase ABC but not by chondrotinase AC, hyaluronidase, or proteolytic enzymes and thus appears to be similar to dermatan sulfate. The results of these studies raise the possibility that lectin-2 functions by interacting with glycosaminoglycans, either associated with the cell surface or with the extracellular matrix.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110107
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    Synergistic stimulation of early events and DNA synthesis by phorbol esters, polypeptide growth factors, and retinoids in cultured fibroblasts (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 79-93 
    Details
    ISSN: 0091-7419
    Keywords: Phorbol esters ; retinoids ; vasopressin ; mitogens ; uridine uptake ; deoxyglucose uptake ; ion fluxes ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: 12-O-Tetradecanoyl-phorbol-13-acetate (TPA), in the absence of serum, acts synergistically with a range of polypeptide growth factors to stimulate DNA synthesis in quiescent Swiss 3T3 cells. These growth factors include epidermal growth factor (EGF), insulin, and the peptide produced by BHK cells transformed by SV-40 virus (fibroblast-derived growth factor, FDGF). Retinoids also show mitogenic synergism with TPA or polypeptide growth factors. The spectrum of mitogenic synergisms displayed by TPA are similar to those of vasopressin, a pituitary peptide. However, TPA and vasopressin do not synergistically interact to stimulate DNA synthesis in quiescent 3T3 cells. This suggests that TPA and vasopressin act via an identical biochemical pathway. Several lines of evidence suggest rapid postreceptor convergence of the mitogenic mechanisms of action of the hormone and the tumor promotor. Thus, vasopressin and TPA both inhibit EGF binding to cellular receptors. Furthermore, TPA and vasopressin induce a similar array of early events in quiescent cells - most strikingly, identical stimulation of Rb+ influx. Stimulation of ion flux is suggested as the possible convergence point of the pathway by which TPA and vasopressin act as mitogens.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110109
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    Tumor metastases and cell-mediated immunity in a model system in DBA/2 mice. VIII. Expression and shedding of Fcγ receptors on metastatic tumor cell variants (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 105-115 
    Details
    ISSN: 0091-7419
    Keywords: tumor metastases ; Fc receptor ; shedding ; tumor variants ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The expression of receptors for the Fc portion of IgG immunoglobin molecules was studied on tumor cell lines with high and low metastatic capacity. Two tumor cell lines from DBA/2 mice that had high metastatic activity, ESb and MDAY-D2, contained a high percentage of Fc receptor positive cells, as detected in a rosette assay with IgG antibody-coated erythrocytes (EA). In contrast, the low metastatic parental line Eb, from which ESb was derived, contained only a low percentage of EA-rosette-forming cells. ESb ascites tumor cells adapted to tissue culture in the presence of 2-mercaptoethanol (2ME) had a high expression of Fc receptors, whereas a cell line adapted to tissue culture in the absence of 2ME had a low expression of Fc receptors.“Soluble” Fc receptors were detectable by their ability to bind to EA and to cause blocking of rosette formation. They were found to be present in fluids from tumor-bearing animals, such as serum and cell-free ascites. Even animals with an ascites tumor of the low-metastatic line Eb contained “soluble” Fc receptors.The results are discussed with regard to their possible significance for tumor metastasis.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110111
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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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    Cholesterol levels and plasma membrane fluidity in 3T3 and SV101-3T3 cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 477-483 
    Details
    ISSN: 0091-7419
    Keywords: virus transformation ; membrane fluidity ; plasma membrane ; filipin ; cholesterol ; spin label ; lectin agglutination ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Polyene antibiotics such as filipin selectively inhibit wheat germ agglutinin-induced agglutination of transformed and malignant cells compared to normal cells (Hatten ME, Burger MM: Biochemistry 18:739, 1979). Since filipin binds specifically to cholesterol, we measured cholesterol levels in 3T3 cells and SV101-3T3 cells. SV101-3T3 cells contained 50-100% more cholesterol per cell than 3T3 cells. Both cell types were starved for cholesterol by growth in lipid-depleted medium plus 25-hydroxycholesterol. The cholesterol level of SV101-3T3 cells decreased by 30-50%, while the level in 3T3 cells remained constant. Filipin-stained SV101-3T3 cells revealed bright patches of filipin under fluorescence microscopy. These patches were absent in 3T3 cells and in SV101-3T3 and 3T3 cells starved for cholesterol. We selectively labeled plasma membranes of these cells with a spin label analog of phosphatidylcholine. The spin label indicated differences in plasma membrane fluidity that may be related to the different cholesterol levels in 3T3 and SV101-3T3 cells.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400110406
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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.400120101
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    Glycosaminoglycans of the plasma membranes of renal tubule and liver cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 15-22 
    Details
    ISSN: 0091-7419
    Keywords: glycosaminoglycans ; glycocalyx ; liver and kidney plasma membranes ; hyaluronic acid ; chondroitin sulfates ; heparin sulfates ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Glycosaminoglycans were isolated from plasma membranes of hepatic and renal tubule cells of guinea pig. Plasmalemma of renal tubule cells contained more total glycosaminoglycans, hyaluronic acid, chondroitin-4 sulfates and chondroitin-6 sulfates, and less dermatan sulfates and heparin sulfates than liver plasma membranes. These glycocalyx components, owing to their polyanionic properties, may have a role in the transport of water, ions, and macromolecules across the cell membrane.
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    URL: http://dx.doi.org/10.1002/jss.400120103
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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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    Action of phorbol esters in cell culture: Mimicry of transformation, altered differentiation, and effects on cell membranes (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 195-208 
    Details
    ISSN: 0091-7419
    Keywords: tumor promoters ; phorbol esters ; plasminogen activator ; epidermal growth factor ; carcinogenesis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The carcinogenic process is usually multifactor in its causation and multistep in its evolution. It is likely that entirely different molecular mechanisms underlie the many steps in this process. In contrast t o initiating carcinogens, the action of the tumor-promoting phorbol esters does not appear t o involve covalent binding t o cellular DNA and they are not mutagenic. Recent studies in cell culture have revealed two interesting biologic effects of the phorbol esters and related macrocyclic plant diterpenes. The first is that at nanomolar concentrations they induce several changes that resemble those seen in cells transformed by chemical carcinogens or tumor viruses. These include altered morphology and increased saturation density, altered cell surface fucose-glycopeptides, decrease in the LETS protein, increased transport of deoxyglucose, and increased levels of plasminogen activator and ornithine decarboxylase. In transformed cells exposed to phorbol esters the expression of these features is further accentuated. Phorbol esters do not induce normal cells to grow in agar but they do enhance the growth in agar of certain transformed cells. The second effect of the phorbol esters is inhibition of terminal differentiation. This effect extends to a variety of programs of differentiation and is reversible when the agent is removed. With certain cell culture systems induction of differentiation, rather than inhibition, is observed. Both the transformation mimetic and the differentiation effects are exerted by plant diterpenes that have tumor-promoting activity but not by congeners that lack such activity. The primary target of phorbol esters appears to be the cell membrane. Early membrane-related effects include enhanced uptake of 2-deoxyglucose and other nutrients, altered cell adhesion, induction of arachidonic acid release and prostaglandin synthesis, inhibition of the binding of epidermal growth factor t o cell surface receptors, altered lipid metabolism, and modifications in the activities of other cell surface receptors. A model of “two stage” carcinogenesis encompassing the known molecular and cellular effects of initiating carcinogens and tumor promoters is presented. According to this model, initiating carcinogens induce stable alterations in the cellular genome but these are not manifested until tumor promoters modulate programs of gene expression and induce the clonal outgrowth of the initiated cell.
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    URL: http://dx.doi.org/10.1002/jss.400120206
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    Regulation of dome formation in differentiated epithelial cell cultures (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 259-272 
    Details
    ISSN: 0091-7419
    Keywords: epithelial transport ; differentiation ; cyclic AMP ; cryoprotective solvents ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Rat mammary (Rama 25) and dog kidney (MDCK) epithelial cell cultures formed ‘domes’ of cells due to fluid accumulation in focal regions between the culture dish and the cell monolayer. Addition of ouabain caused collapse of domes, suggesting that transport functions were required for maintenance of domes.Dome formation in both epithelial cell lines was stimulated by a broad spectrum of known inducers of erythroid differentiation in Friend erythroleukemia cells. Among these inducers were: (1) polar solvents such as dimethylsulfoxide, dimethylformamide, and hexamethylene bisacetamide; (2) purines such as hypoxanthine, inosine, and adenosine; (3) low-molecular-weight fatty acids such as n-butyrate; and (4) conditions expected to elevate levels of cyclic AMP. In the latter group were activators of adenylate cyclase such as cholera toxin and prostaglandin E1; cyclic AMP phosphodiesterase inhibitors such as theophylline and 1-methyl-3-isobutylxanthine; and analogs of cyclic AMP.Induction of domes occurred 15-30 h after addition of inducer to the culture medium. Induction by chemicals was serum-dependent and required protein synthesis but not DNA synthesis. Induced dome formation was reversible after removal of inducer, requiring the contiuous presence of inducer. Reversal was also observed after either removal of serum or addition of inhibitors of protein synthesis.These results suggest the hypothesis that domes arise in these epithelial cultures by a process that is similar to cell differentiation and is influenced by cyclic AMP.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400120210
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    Protein-RNA interactions during TMV assembly (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 305-320 
    Details
    ISSN: 0091-7419
    Keywords: tobacco mosaic virus ; structure ; RNA-binding site ; assembly ; protein-nucleic acid interactions ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A review of the structural studies of tobacco mosaic virus (TMV) is given. TMV is essentially a flat helical microcrystal with 16 1/3 subunits per turn. A single strand of RNA runs along the helix and is deeply embedded in the protein. The virus particles form oriented gels from which high-resolution X-ray fiber diffraction data can be obtained. This may be interpreted by the use of six heavy-atom derivatives to give an electron density map at 0.4 nm resolution from which the RNA configuration and the form of the inner part of the protein subunit may be determined. In addition, the protein subunits form a stable 17-fold two-layered disk which is involved in virus assembly and which crystallizes. By the use of noncrystallographic symmetry and a single heavy-atom derivative, it has been possible to solve the structure of the double disk to 0.28 nm resolution. In this structure one sees that an important structural role is played by four alpha-helices, one of which (the LR helix) appears to form the main binding site for the RNA. The main components of the binding site appear to be hydrophobic interactions with the bases, hydrogen bonds between aspartate groups and the sugars, and arginine salt bridges to the phosphate groups. The binding site is between two turns of the virus helix or between the turns of the double disk. In the disk, the region proximal to the RNA binding site is in a random coil until the RNA binds, whereupon the 24 residues involved build a well-defined structure, thereby encapsulating the RNA.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/jss.400120304
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    The regional association of actin and myosin with sites of particle phagocytosis (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 369-384 
    Details
    ISSN: 0091-7419
    Keywords: phagocytosis ; actin ; myosin ; macrophages ; immunofluorescence ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Contractile proteins are thought to play a causative role in motile processes such as phagocytosis. In order to investigate their role in phagocytosis further, simultaneous immunofluorescence localization of F-actin and myosin was carried out in resident mouse peritoneal macrophages after phagocytosis of opsonized zymosan particles. Both actin and myosin appeared to concentrate rapidly at sites of particle phagocytosis. The observed concentration of both proteins at such sites preceded ultimate particle engulfment. Cytochalasin B, a drug which was shown to block pseudopod extensions around the particle, did not prevent the concentration of the two contractile proteins at cell-particle binding sites. This result ruled out path-length effects as an explanation for the observed concentration of actin and myosin at phagocytic sites. Kinetic analysis showed that actin rapidly concentrates at particle-cell binding sites within minutes (or less) of contact with cell surface. The two proteins are present throughout the engulfment phase until and after ingestion is complete. Finally, at later times the particles become clustered over the cell nucleus and the particle-associated actin-myosin seen earlier is no longer evident.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120308
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  • 136
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    Rhodopsin phosphorylation suggests biochemical heterogeneities of retinal rod disks (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 419-424 
    Details
    ISSN: 0091-7419
    Keywords: frog retina ; rod membranes ; rhodopsin ; phosphorylation ; disk heterogeneity ; papainolysis ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Frogs (Rana pipiens) were injected subcutaneously with (3H)-leucine and allowed to incorporate the radioactive amino acid into newly assembled disks in the retinal rod outer segment. The labeled disks served as a temporal market for following the turnover of rod outer segments. Animals were killed at different times after injection and outer segments were isolated and phosphorylated with ATP in the light. The visual pigment (as isorhodopsin) was regenerated with 9-cis retinal, extracted, and chromatographed on epichlorohydrin triethanolamine cellulose so that phosphorylated pigment could be separated from unphosphorylated pigment. The ratio of (3H)-radioactivity of phosphorylated pigment to that of unphosphorylated pigment was then plotted against the time after injection. The ratio was high when (3H)-labeled disks were largely associated with the basal region of the rod and decreased as the labeled disks moved toward the rod apical region. The results were interpreted as suggesting that newer disks are phosphorylated preferentially to older disks. Papain digestion of (3H)-labeled disks indicated that rhodopsin in newer disks is more susceptible to proteolysis than that in older disks.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120402
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  • 137
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    Isolation and characterization of human placental chorionic villar extracellular matrix (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 457-466 
    Details
    ISSN: 0091-7419
    Keywords: human placental basement membrane ; extracellular matrix ; human chorionic villar basement membrane ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The cell-free extracellular matrix of human placental chorionic villi has been prepared by a procedure employing extraction of the terminal villar fragments with the detergents Triton X-100 and sodium deoxycholate. The isolated human placental extracellular matrix retains an intact, but collapsed, histoarchitecture, as observed by scanning and transmission electron microscopy. It remains intact, in large part because of the presence of continuous sheets of villar basement membranes and associated interstitial collagen fibers and scattered patches of fibrin. The staining characteristics and chemical composition of the isolated human placental extracellular matrix are similar to those reported for basement membranes in several tissues and indicate the presence of collagen-like and glycoprotein components in this preparation. Gel electrophoresis of urea-SDS-mercaptoethanol extracts of the matrix showed that it consists of several polypeptide components of various molecular weights, some of which are associated into high molecular weight complexes by disulfide bonds.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120405
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  • 138
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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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  • 139
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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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  • 140
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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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  • 141
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    Growth of kidney epithelial cells in hormone-supplemented, serum-free medium (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 207-216 
    Details
    ISSN: 0091-7419
    Keywords: renal epithelium ; primary cultures ; prostaglandins ; mammalian cell growth ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Madin Darby canine kidney cells can grow in synthetic medium supplemented with 5 factors - insulin, transferrin, prostaglandin E1, hydrocortisone and triiodothyronine - as a serum substitute. These 5 factors permit growth for one month in the absence of serum, and a growth rate equivalent to that observed in serum-supplemented medium. Dibutyryl cAMP substitutes for prostaglandin E1 in the medium, suggesting that increased growth of Maden Darby canine kidney cells results from increased intracellular cAMP. Potential applications of the serum-free medium are discussed. The medium permits the selective growth of primary epithelial cell cultures in the absence of fibroblast over-growth, and a defined analysis of the mechanisms by which hormones regulate hemicyst formation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110210
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  • 142
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    Human fibrosarcoma cells produce fibronectin-releasing peptides (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 11 (1979), S. 217-225 
    Details
    ISSN: 0091-7419
    Keywords: fibrosarcoma culture media ; gel permeation chromatography ; fibronectin-radioimmunoassay ; fibronectin-releasing peptides ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A sensitive radioimmunoassay, specific for human fibronectin, was used to measure the ability of certain biologically active polypeptides to release fibronectin from cultured human lung fibroblasts into their culture media. Concentrated, serum-free culture supernatant from a human fibrosarcoma cell line was fractionated by gel filtration chromatography in the presence of acetic acid. Various polypeptides with molecular weights between 46,000 and 6,000 were tested for their ability to release fibronectin from cells. The column fraction, containing polypeptides with an apparent molecular weight of 10,000, exhibited the ability to rapidly release fibronectin from target cells. The activity could be inhibited by phenylmethyl sulphonylfluoride. Several other hormonal factors, tested in parallel with the column fractions, failed to show this effect. The 10,000 dalton molecular weight polypeptides may represent a family of cellular gene products responsible for maintenance of low levels of surface associated fibronectin in fibrosarcoma cells and thus be related to their infiltrating properties by preventing the formation of the extracellular matrix.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400110211
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  • 143
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    Alteration of human breast tumor cell membrane functions by chromosome-mediated gene transfer (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 355-367 
    Details
    ISSN: 0091-7419
    Keywords: Alkaline phosphatase ; chromosome-mediated gene transfer ; human breast tumor cells ; hydrocortisone ; lipochromes ; membrane bound enzymes ; nucleoside uptake ; thymidine kinase ; thymidine transport ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: BOT-2 cells (human breast tumor origin) have an impaired ability to utilize exogenous thymidine. Previous studies revealed this deficiency to be the permeation event rather than phosphorylation, since the cells have active thymidine kinase. Chromosome-mediated gene transfer was used to transfer genetic information in the form of metaphase chromosomes, from HeLa-65 cells to the BOT-2 cells, correcting the permease deficiency. Poly-L-ornithine or lipochromes were used for facilitation of chromosome uptake. After selection on HAT medium, transferant clones were isolated at a frequency of 4 X 10-5 and 1 X 10-5, respectively. Transferants MGP-1 and MGL-1 are stable after 18 months and have been characterized on the bases of purine and pyrimidine nucleoside uptake, relative thymidine kinase activities, alkaline phosphatase activities, and hydrocortisone-induced alkaline phosphatase activity. MGP-1 demonstrates positive thymidine uptake and incorporates radiolabeled thymidine into DNA. MGL-1 remains thymidine transport-deficient and survives on HAT by increasing endogenous dihydrofolate reductase activity. Alkaline phosphatase activity in MGL-1 is similar to HeLa-65, 2% of that in BOT-2, and in addition, is inducible 25-30-fold by 3 μM hydrocortisone. We have separated, genetically, a thymidine permease function from phosphorylation in cells of human origin and have transferred genetic information for the regulation of alkaline phosphatase.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120307
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  • 144
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    Analysis of transmembrane proteins from eukaryotic cells (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 403-417 
    Details
    ISSN: 0091-7419
    Keywords: mouse L-929 cells ; “inside-out” configuration ; gel electrophoresis ; lectin-binding proteins ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The topography and properties of plasma membrane proteins from mouse L-929 cells are studied by comparing their availability for enzymatic labeling on the external and internal surfaces of the membrane. In order to study the internal surface, phagolysosomes are prepared from cells after they ingest latex particles. The plasma membrane surrounding these seems to have an “inside-out” orientation. The sugars of the membrane glycoproteins in intact phagolysosomes are not available for interaction with lectins or available for periodate-borotritide labeling. A comparison of the lectin-binding proteins lableled by lactoperoxidase-catalyzed iodination on the external cell surface with those labeled on the internal cell surface suggests that a variety of plasma membrane glycoproteins span the lipid bilayer.Using two-dimensional gel electrophoresis it has been shown that selected proteins are labeled at both the internal and external faces of the plasma membrane. Analysis of the 2-D gel electrophoregrams reveals that there are two distinct prominent proteins at 60,000 and 100,000 daltons which are enzymatically iodinated from both sides of the membrane. The partial hydrolysis of the 100,000 dalton protein reveals that different peptides are iodinated when the iodination is performed on intact cells or on the phagolysosomes. These proteins are extensively phosphorylated in cells incubated with inorganic 32P. We conclude that the phagolysosome is probably oriented in an “inside-out” configuration and that this membrane preparation can be used to study the topographic organization of membrane proteins.The use of oriented membranes, selective labeling of proteins, and affinity separation of proteins in combination with gel electrophoresis to define the position and properties of proteins is discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120310
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  • 145
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    Mitogenic effects of murine serum and fibroblast growth factor on EGF nonproliferative variants of 3T3 (1979)
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 12 (1979), S. 467-470 
    Details
    ISSN: 0091-7419
    Keywords: epidermal growth factor ; fibroblast growth factor ; cell division ; mitogenesis ; growth control ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The enhanced ability of murine serum to support growth of 3T3 cells, when compared with fetal calf serum, is also evident on variants of 3T3 cells lacking the ability to bind epidermal growth factor (EGF). Variant 3T3 cell lines unable to bind EGF also retain a mitogenic response to fibroblast growth factor.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jss.400120406
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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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    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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