title: Polyoma small and middle T antigens and SV40 small t antigen form stable complexes with protein phosphatase 2A.
abstract: We have purified the 36 and 63 kd cellular proteins known to associate with polyomavirus middle and small tumor (T) antigens and SV40 small t antigen. Microsequencing of the 36 kd protein indicated that it was probably identical to the catalytic subunit of protein phosphatase 2A (PP2A). Identity was confirmed by comigration on two-dimensional (2D) gels and by 2D analysis of complete chymotryptic digests. In addition, PP2A-like phosphatase activity was detected in immunoprecipitates of wild-type middle T. Immunoblotting experiments, comigration on 2D gels, and 2D analysis of limit chymotryptic digests demonstrated that the 63 kd protein, present in the middle T complex in approximately equimolar ratio to the 36 kd protein, is a known regulatory subunit of the PP2A holoenzyme. Finally, the 36 kd PP2A catalytic subunit can be immunoprecipitated by anti-pp60c-src antisera only from cells expressing wild-type middle T. These results suggest that complex formation between PP2A and T antigens may be important for T antigen-mediated transformation.
authors: Division of Cellular and Molecular Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115.
authors: D C
authors: DC
authors: Pallas
authors: L K
authors: LK
authors: Shahrik
authors: B L
authors: BL
authors: Martin
authors: S
authors: S
authors: Jaspers
authors: T B
authors: TB
authors: Miller
authors: D L
authors: DL
authors: Brautigan
authors: T M
authors: TM
authors: Roberts
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming; D001665:Binding Sites; D002460:Cell Line; D015151:Immunoblotting; D046911:Macromolecular Substances; D051379:Mice; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000302:isolation & purification; D010449:Peptide Mapping; D010749:Phosphoprotein Phosphatases / Q000302:isolation & purification / Q000378:metabolism*; D010765:Phosphorylase Phosphatase / Q000378:metabolism; D011120:Polyomavirus / Q000276:immunology*; D011485:Protein Binding; D054648:Protein Phosphatase 2; D013539:Simian virus 40 / Q000276:immunology*; D014357:Trypsin
chemical_list: D000952:Antigens, Polyomavirus Transforming; D046911:Macromolecular Substances; D010446:Peptide Fragments; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; D010765:Phosphorylase Phosphatase; D014357:Trypsin