Monomer molecular weight of T antigen from simian virus 40-infected and transformed cells.
T-antigens from simian virus 40 (SV 40)-transformed and lytically infected cells have been isolated by immunoprecipitation and their molecular weights estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. T-antigen from SV40-transformed mouse and hamster cells has an apparent molecular weight of 94,000 whereas that from several lines of SV40-infected monkey cells is 84,000. In a wheat germ cell-free system, mRNA from either transformed or productively infected cells is translated into a 94,000 species. Experiments with the protease inhibitors L-l-(tosylamide-2-phenyl)ethylchloromethyl ketone HCl and N-alpha-p-tosyl-L-lysylchloromethyl ketone HCl suggest that the 84,000 species of T-antigen found in infected cells is derived from the larger species by proteolytic cleavage. Further, the cleavage pathway probably involves a two-step reaction with an 89,000 intermediate. The biological significance of the two molecular weight forms of T-antigen is unknown, but the possibility that they have different physiological activities is discussed.
D000956:Antigens, Viral / Q000032:analysis*; D002471:Cell Transformation, Neoplastic; D002474:Cell-Free System; D004591:Electrophoresis, Polyacrylamide Gel; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D012367:RNA, Viral / Q000378:metabolism; D013539:Simian virus 40 / Q000032:analysis* / Q000254:growth & development / Q000276:immunology; D014764:Viral Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000378:metabolism
D000956:Antigens, Viral; D011498:Protein Precursors; D012367:RNA, Viral; D014764:Viral Proteins; D010447:Peptide Hydrolases