Polyoma small and middle T antigens and SV40 small t antigen form stable complexes with protein phosphatase 2A.
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Pallas DC, Shahrik LK, Martin BL, Jaspers S, Miller TB, Brautigan DL, Roberts TM
Polyoma small and middle T antigens and SV40 small t antigen form stable complexes with protein phosphatase 2A.
Cell. 1990 Jan 12;60(1):167-76.
- PubMed ID
- 2153055 [ View in PubMed]
- 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.