Translation of polyoma virus T antigens in vitro.

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Abstract
Polyoma virus-specific RNA isolated from the cytoplasm of lytically infected cells can be translated in vitro to yield 3 T [tumor] antigens, of MW approximately 90,000, 60,000 and 22,000. The tryptic peptide patterns of the T antigens synthesized in vitro are similar or identical to the patterns of the corresponding proteins in polyoma-infected cells. All 3 proteins incorporate methionine donated from initiator tRNA in vitro, Polyoma c[complementary]RNA codes for a protein that is slightly larger than the 22,000 T antigen and that, by other criteria, is similar to the 22,000 T antigen. Translation of cRNA does not yield the 90,000 and 60,000 T antigens, suggesting that the generation of the mRNA for these T antigens requires the removal of intervening sequences. The mRNA for the 90,000 T antigen is smaller than the mRNAs for the 22,000 and 60,000 proteins. All 3 proteins share common NH2-terminal sequences, and the 60,000 T antigen may be translated partially in a different reading frame from sequences also coding for the 90,000 T antigen. The demonstration that polyoma virus codes for 3 different T antigens raises the possibility that all 3 proteins may be involved in cell transformation.