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  • 1
    Digitale Medien
    Digitale Medien
    An activating amino acid substitution in the c-abl oncogene protein fails to produce a local conformational change (1991)
    Springer
    The protein journal 10 (1991), S. 437-441 
    Details
    ISSN: 1573-4943
    Schlagwort(e): Conformational energy ; three-dimensional structure ; amino acid substitution ; c-abl oncogene ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Thebcr-abl chimeric gene of Philadelphia chromosome positive chronic myelogenous leukemias is only weakly transforming. This transformation activity is greatly enhanced by a Lys-for-Glu substitution at position 832 in the c-abl gene, as occurs in the highly transforming v-abl genes. It has been suggested that this mutation results in a significant structural change in the encoded protein product. Using conformational energy analysis, we have determined the allowed low-energy conformations for residues 828–836 of this protein with Lys and Glu at position 832. In both cases, the overwhelmingly preferred conformation for this region is a bend-helix motif. The helix terminates at residue 836, and there are no discernible differences in conformation between the Lys- and Glu-containing sequences. These results suggest that the activating amino acid substitution at position 832 in the c-abl protein product does not produce its effect via a local conformational change.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025258
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  • 2
    Digitale Medien
    Digitale Medien
    Structural implications of the substitution of Val for met at residue 239 in the alpha chain of human platelet glycoprotein IB (1994)
    Springer
    The protein journal 13 (1994), S. 629-633 
    Details
    ISSN: 1573-4943
    Schlagwort(e): von Willebrand factor ; platelet ; amino acid substitution ; conformational energy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01890461
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  • 3
    Digitale Medien
    Digitale Medien
    Correlation of structure with transforming activity of the P21 proteins with substitutions of L-amino acids for Gly at position 13 (1985)
    Springer
    The protein journal 4 (1985), S. 345-352 
    Details
    ISSN: 1573-4943
    Schlagwort(e): conformational energy ; three-dimensional structure ; amino acid substitution ; P21 proteins ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effects of amino acid substitutions for Gly 13 on the structure of the transforming region (Leu 6-Gly 15) of the P21 proteins have been explored using conformational energy calculations. It has been found that the substitution of Asp for Gly at this position results in a protein capable of transforming cells into malignant ones. Proteins that contain Ser at position 13 (but no other substitutions), however, transform cells with a greatly reduced activity. The transforming peptide with Asp 13 adopts a conformation that is different from the one for the peptide from the normal protein (with Gly 12 and Gly 13) and that may result in expression of a higher energy malignancy-producing form. The Ser-containing peptide adopts as its lowest energy conformation one that is identical to that of the peptide from the normal protein, thus explaining its lack of transforming activity. From analysis of the interactions preventing the Asp 13-containing peptide from adopting the “normal” conformation, it is predicted that substitutions of amino acids with branched side chains atC β, such as Val, Ile, and Thr, should promote cell transformation. This prediction with Val has recently been confirmed in genetic experiments.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025175
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  • 4
    Digitale Medien
    Digitale Medien
    Structural effects of amino acid substitutions on the P21 proteins: Evidence for a malignant conformation (1985)
    Springer
    The protein journal 4 (1985), S. 353-362 
    Details
    ISSN: 1573-4943
    Schlagwort(e): conformational energy ; three-dimensional structure ; amino acid substitution ; P21 proteins ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The conformational effects of different amino acid substitutions for Gly at position 12 in theras-oncogene-encoded P21 proteins have been investigated using conformational energy calculations. Mutations that cause amino acid substitutions for Gly 12 result in a protein that produces malignant transformation of cells. It had previously been shown that substitution of Val, Lys, or Ser for Gly at position 12 results in a major conformational change, and that the preferred lowest energy structure for each of the substituted peptides is identical. It is now found that substitution for Gly 12 of other amino acids that have widely disparate helix-nucleating potentials and completely different side chains (Asp, Asn, Cys, Phe, Tle, Leu, and Ala) all produce this identical lowest energy conformation. This finding is consistent with the recent results of site-specific mutagenesis experiments showing that P21 proteins containing these amino acids at position 12 all promote malignant transformation of cells and suggests the existence of a “malignancy-causing” conformation for the P21 proteins.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025176
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  • 5
    Digitale Medien
    Digitale Medien
    Conformational effects of amino acid substitutions at positions 10, 12, and 13 in the P21 protein (1989)
    Springer
    The protein journal 8 (1989), S. 79-86 
    Details
    ISSN: 1573-4943
    Schlagwort(e): conformational energy ; amino acid substitution ; P21 protein ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Substitutions of amino acids for Gly 12 or Gly 13 in theras oncogene-encoded P21 proteins have been demonstrated to produce unique structural changes in these proteins that correlate with their ability to produce cell transformation. For example, the P21 proteins with Arg 12 or Val 13 are both known to be actively transforming. Recent site-specific mutagenesis experiments on the transforming Arg 12 protein have found that the substitution of Val for Gly 10 has no effect on transforming activity whereas the substitution of Val for Gly 13 led to a loss of transforming activity. In this study, we examine the structural effects of these substitutions on the amino terminal hydrophobic decapeptide (Leu 6-Gly 15) of P21 using conformational energy analysis. The results show that the transforming proteins with Gly 10 and Arg 12 or Val 10 and Arg 12 can both adopt the putative malignancy-causing conformation, whereas, for the nontransforming protein with Arg 12 and Val 13, this conformation is energetically disallowed. These results further support the theory that due to structural changes the transforming P21 proteins are unable to bind to some regulatory cellular element which may be the recently identified binding protein responsible for the induction of increased GTPase activity in normal P21 compared with transforming mutants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025080
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  • 6
    Digitale Medien
    Digitale Medien
    Conformational effects of the substitution of ARG for GLY 13 in theras oncogene-encoded P21 protein (1988)
    Springer
    The protein journal 7 (1988), S. 349-354 
    Details
    ISSN: 1573-4943
    Schlagwort(e): conformational energy ; amino acid substitution ; position 13 ; P21 protein ; transformation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The effect of the substitution of Arg for Gly 13 on the structure of the transforming region decapeptide (Leu 6-Gly 15) of the ras oncogene encoded P21 protein has been investigated using conformational energy analysis. A human malignancy has been identified that contains a ras gene with a single mutation in the thirteenth codon such that the encoded protein would have Arg substituted for Gly at this position, and transfection of cells in culture with this gene results in malignant transformation. Conformational analysis demonstrates that the Arg 13 decapeptide adopts a conformation identical to that for other peptides with substitutions at position 13 (Asp 13, Val 13) from transforming proteins that is distinctively different from that for peptides (Gly 13, Ser 13) from normal, nontransforming proteins. This is found to be an indirect effect resulting from changes in the conformation of Gly 12 produced by substitutions at position 13. These results are consistent with recent analysis of crystallographic data of proteins on conformational preferences for glycine in tripeptide sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01024884
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  • 7
    Digitale Medien
    Digitale Medien
    Conformation of the metastasis-inhibiting laminin pentapeptide (1989)
    Springer
    The protein journal 8 (1989), S. 149-157 
    Details
    ISSN: 1573-4943
    Schlagwort(e): conformational energy ; three-dimensional structure ; amino acid substitution ; laminin pentapeptide ; metastasis inhibition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The binding of cancer cells to the basement membrane glycoprotein laminin appears to be a critical step in the metastatic process. This binding can be inhibited competitively by a specific pentapeptide sequence (Tyr-Ile-Gly-Ser-Arg) of the laminin B1 chain, and this peptide can prevent metastasis formationin vivo. However, other similar pentapeptide sequences (e.g., Tyr-Ile-Gly-Ser-Glu) have been found to be much less active in metastasis inhibition, raising the possibility that such amino acid substitutions produce structural changes responsible for altering binding to the laminin receptor. In this study, conformational energy analysis has been used to determine the three-dimensional structures of these peptides. The results indicate that the substitution of Glu for the terminal Arg produces a significant conformational change in the peptide backbone at the middle Gly residue. These results have important implications for the design of drugs that may be useful in preventing metastasis formation and tumor spread.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01025085
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  • 8
    Digitale Medien
    Digitale Medien
    Conformational changes induced by the transforming amino acid substitution in the transmembrane domain of theneu oncogene-encoded p185 protein (1989)
    Springer
    The protein journal 8 (1989), S. 749-756 
    Details
    ISSN: 1573-4943
    Schlagwort(e): conformational energy ; three-dimensional structure ; amino acid substitution ; neu oncogene ; p185 protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Theneu oncogene is frequently found in certain types of human carcinomas and has been shown to be activated in animal models by nitrosourea-induced mutation. The activating mutation in theneu oncogene results in the substitution of a glutamic acid for a valine at position 664 in the transmembrane domain of the encoded protein product of 185 kda (designated p185), which, on the basis of homology studies, is presumed to be a receptor for an as yet unidentified growth factor. It has been proposed that activating amino acid substitutions in this region of p185 lead to a conformational change in the protein which causes signal transduction via an increase in tyrosine kinase activity in the absence of any external signal. Using conformational energy analysis, we have determined the preferred three-dimensional structures for the transmembrane decapeptide (residues 658–667) of the p185 protein with valine and glutamic acid at the critical position 664. The results indicate that the global minimum energy conformation of the decapeptide from the normal protein with Val at position 664 is an α-helix with a sharp bend (CD* conformation at residues 664 and 665) in this region, whereas the global minimum conformation for the decapeptide from the mutant transforming protein with Glu at position 664 assumes an all α-helical configuration. Furthermore, the second highest energy conformation for the decapeptide from the normal protein is identical to the global minimum energy conformation for the decapeptide from the transforming protein, providing a possible explanation why overexpression of the normal protein also has a transforming effect. These results suggest there may be a normal and a transforming conformation for theneu-encoded p185 proteins which may explain their differences in transforming activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01024899
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  • 9
    Digitale Medien
    Digitale Medien
    A comparative study of the chromosomes of the Norway rat (Rattus norvegicus ERXL.) and the black rat (Rattus rattus L.)This paper (with another study to be published later) was submitted to the faculty of the Bussey Institution, Harvard University, in partial fulfillment of the requirements for the degree of Doctor of Science. It was prepared under the direction of Dr. W. E. Castle. Acknowledgment is due Prof. T. S. Painter for advice on technique and the examination of some of the material herein presented. (1927)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 44 (1927), S. 515-538 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: By the use of a satisfactory technique, excellently preserved spermatogenetic tissue was had both for Rattus rattus and Rattus norvegicus. The careful examination of twelve spermatogonial cells of the former species and of twenty in the latter species shows that R. rattus has forty diploid chromosomes and R. norvegicus, forty-two. A careful examination of the haploid cells of both species, both in the first and in the second spermatocyte divisions, confirms the diploid determinations.Both species have an unequal pair in the spermatogonial divisions and the finding of a similar unequal pair in the first spermatocyte division constitutes the evidence for an X-Y mechanism in each. A comparison of the morphology of the first spermatocyte tetrads in the two species reveals the presence of a large K-shaped chromosome in R. norvegicus which is not present in R. rattus. Furthermore, a comparison of the X-Y complex in both the spermatogonial and first spermatocyte divisions shows that these are morphologically different in the two species, the Y in particular being markedly dissimilar in size. A short discussion as to the bearing of these findings on the questions of the origins of the two species and their known intersterility is presented. The marked similarity of the tetrads of the black rat to those described for the mouse is noted.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050440306
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  • 10
    Digitale Medien
    Digitale Medien
    The growth, maturation and atresia of ovarian eggs in the rabbitThis investigation was aided by a grant from the National Research Council Committee for Problems of Sex. (1937)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 61 (1937), S. 351-383 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: A study is made of the development of ovarian ova in mature rabbit does before and during various stages of pregnancy and after the injection of thyroid and anterior-pituitary-like hormones. No appreciable ovogenesis during sexual maturity was found. Nine types of ovarian follicle are distinguished according to size and degree of development. Full ovum size is reached in pre-antral follicles, and is marked by the formation of a dictyate nucleus and slight reduction in nuclear size. Full follicle size is attained much later. The nature of follicle migration in the course of development is described. Ovum migration within the follicle is found to be a consequence of the nature of the egg's attachments to the follicular epithelium. The least atresia is found in young oocytes (10%), the larger follicles showing about 60% atretic at all stages of the reproductive cycle. The hormone preparations administered affect only the largest follicles and their contained ova.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1050610207
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