Cell-free translation of virion RNA from nondefective and transformation-defective Rous sarcoma viruses

Abstract

Nondefective and transformation-defective virion subunit RNA from 2 strains of Rous sarcoma virus (RSV) were translated in cell-free systems derived from Krebs IIA [mouse] ascites cells, wheat germ and [mouse] L-cells [fibroblasts]. In each case the predominant viral-specific product was a polypeptide of MW 76,000 that is related to the internal viral group-specific antigens, as judged by immunoprecipitation with monospecific antisera and tryptic peptide fingerprinting. No difference could be detected between the translation products of 35S RNA from nondefective and transformation-defective RSV virions, nor of 35S RNA from different strains of RSV. The 76,000 MW polypeptide synthesized in response to 35S RNA in vitro was labeled with formyl-methionine from initiator tRNA. Models of viral protein synthesis are discussed in the light of these results, and arguments positioning the group-specific antigen gene at the 5'' end of the 35S RNA are presented.