Sites of synthesis of viral proteins in avian sarcoma virus-infected chicken cells

Abstract

The sites of synthesis of avian sarcoma virus-specific proteins in infected chicken cells were determined by immunoprecipitation of the products synthesized in vitro by free and membrane-bound polyribosomes; 85% of Pr76, the precursor of the viral internal structural proteins (group-specific antigens) was synthesized on free polyribosomes and 15% was synthesized on membrane-bound polyribosomes. Pr92, the glycosylated precursor of the viral glycoproteins (gp85 and gp35), was synthesized exclusively on membrane-bound polyribosomes, which is consistent with its role as a membrane protein. For pp60src, the product of the avian sarcoma virus src gene, 90% was synthesized on free polyribosomes and 10% was detected on membrane-bound polyribosomes. The implications of these results with respect to the subcellular location of pp60src are discussed.