title: Two phosphorylated subclasses of polyomavirus large T antigen that differ in their modes of association with the cell nucleus.
abstract: Two classes of polyomavirus large T antigen were distinguished, differing in their modes of association with the cell nucleus. A weakly associated class, the nucleoplasmic T antigen, representing 30 to 40% of the total, was solubilized when cells were lysed isotonic buffer at pH 7.2. A more tightly bound class retained in isolated nuclei, the retained T antigen, was extractable either at pH 9.0 or in 2 M NaCl. The retained T antigen contained an additional mole of phosphate, 4 mol of PO4 per mol of T antigen, compared with the nucleoplasmic T antigen (3 mol of PO4 per mol of T antigen). Limit digestion with staphylococcal V8 protease yielded equivalent amounts of five peptides ranging in size from 7.5 to 20 kilodaltons. Additional phosphorylation within a 12-kilodalton peptide accounted for most of the difference in phosphate content between retained and nucleoplasmic T-antigen classes.
mesh_terms: D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor / Q000145:classification* / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D003600:Cytosol / Q000032:analysis; D005347:Fibroblasts / Q000032:analysis; D051379:Mice; D009856:Oncogene Proteins, Viral / Q000145:classification* / Q000378:metabolism; D010449:Peptide Mapping; D010750:Phosphoproteins / Q000145:classification / Q000378:metabolism; D010766:Phosphorylation; D011120:Polyomavirus / Q000032:analysis* / Q000276:immunology; D011485:Protein Binding
chemical_list: D000952:Antigens, Polyomavirus Transforming; D000957:Antigens, Viral, Tumor; D009856:Oncogene Proteins, Viral; D010750:Phosphoproteins