Messenger ribonucleoproteins of cells infected by simian virus 40 contain large T-antigen.
In monkey or mouse cells undergoing lytic or transforming infection with simian virus 40, about 10% of large tumor antigen (T-antigen) molecules were consistently present in the cytoplasm and 90% in the nucleus. The bulk of cytoplasmic large T-antigen cosedimented in linear sucrose gradients with polyribosomes (150-500 S) and with messenger ribonucleoproteins sedimenting within 20-80 S. As determined by centrifugation in discontinuous sucrose gradients, its apparent density (1.2-1.3 g/ml) corresponded to that of ribonucleoproteins. In contrast, the bulk of nuclear T-antigen sedimented between 5-20 S and its apparent density (1.1 g/ml) corresponded to that of free protein. Nuclear T-antigen added before cell fractionation did not bind to cytoplasmic constituents. After dissociation of purified polyribosomes with puromycin/KCl or EDTA, cytoplasmic large T-antigen cosedimented with the released messenger ribonucleoproteins containing poly(A)-rich messenger RNA. Upon hydrolysis of the RNA with RNase A, large T-antigen exhibited the sedimentation properties and density of free protein. The results suggest that cytoplasmic large T-antigen is associated with messenger ribonucleoproteins.
D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface / Q000302:isolation & purification*; D000956:Antigens, Viral / Q000302:isolation & purification*; D002467:Cell Nucleus / Q000378:metabolism; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D003593:Cytoplasm / Q000032:analysis; D000882:Haplorhini; D051379:Mice; D009698:Nucleoproteins / Q000302:isolation & purification*; D012333:RNA, Messenger / Q000302:isolation & purification*; D012261:Ribonucleoproteins / Q000302:isolation & purification*; D013539:Simian virus 40 / Q000276:immunology*
D000945:Antigens, Differentiation, T-Lymphocyte; D000954:Antigens, Surface; D000956:Antigens, Viral; D009698:Nucleoproteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins