Document Detail


SV40 T-antigen as a dual oncogene: structure and function of the plasma membrane-associated population.
MedLine Citation:
PMID:  2552888     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
SV40 T-antigen (T-ag) is localized in both the nucleus (nT-ag) and plasma membrane (pmT-ag) of cells and provides multiple functions necessary for cell transformation. The pmT-ag population is structurally very similar to the nT-ag. Transport to the cell surface is by an unknown mechanism that does not involve the secretory pathway. The disposition of T-ag in the membrane exposes both the amino and the carboxyl terminus on the exterior of the cell. Nuclear-transport-defective mutants of T-ag can transform established cells in culture, but not primary cells, suggesting that non-nuclear forms of T-ag may mediate some transformation-related process(es). A non-cytolytic protein extraction technique utilizing 1-butanol solubilized from SV40-transformed cells a multimeric complex composed of pmT-ag and at least five cellular proteins ranging in size from 35,000 (35K) to 60K M. Both amino- and carboxylterminal T-ag-specific monoclonal antibodies co-precipitated T-ag and the 35-60K Mr proteins, but antibodies against the internal portion of T-ag precipitated only uncomplexed T-ag. The growth state of the cells markedly influenced the expression of the T-ag-containing surface complexes; more complexes were recovered from actively dividing cells than from confluent cell cultures, and suspension cells yielded more complexes than cells on a substratum. The complex exhibited a highly dynamic association with the cell membrane, as demonstrated by pulse-chase analysis. The characteristics of growth-dependent expression and rapid turnover rate suggest a functional role for the membrane complex. The identities of the cellular proteins in the complex with pmT-ag are unknown, although one member (56K) is recognized by p53-specific monoclonal antibodies.
Authors:
J S Butel; D L Jarvis; S A Maxwell
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.; Review    
Journal Detail:
Title:  Annals of the New York Academy of Sciences     Volume:  567     ISSN:  0077-8923     ISO Abbreviation:  Ann. N. Y. Acad. Sci.     Publication Date:  1989  
Date Detail:
Created Date:  1989-11-08     Completed Date:  1989-11-08     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7506858     Medline TA:  Ann N Y Acad Sci     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  104-21     Citation Subset:  IM    
Affiliation:
Division of Molecular Virology, Baylor College of Medicine, Houston, Texas 77030.
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MeSH Terms
Descriptor/Qualifier:
Animals
Antigens, Polyomavirus Transforming / genetics*
Cell Membrane / immunology
Cell Transformation, Neoplastic
Humans
Oncogenes*
Simian virus 40 / genetics*,  immunology
Grant Support
ID/Acronym/Agency:
CA09197/CA/NCI NIH HHS; CA22555/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/Antigens, Polyomavirus Transforming

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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