Half-life of the Rous sarcoma virus transforming protein pp60src and its associated kinase activity.
The half-life of metabolically labeled pp60src of the Prague A strain of Rous sarcoma virus and of several transformation-defective, temperature-sensitive mutants was investigated by pulse-labeling infected cells with [35S]methionine, chasing for different times, and immunoprecipitating pp60src with tumor-bearing rabbit serum. These experiments showed that pp60src has a short half-life of approximately 60 min under normal physiological conditions and that the mutant pp60src proteins have similar half-lives to the wild type, irrespective of whether the cells are kept at the nonpermissive (42 degrees C) or permissive (35 degrees C) temperature. The half-life of the pp60src -associated kinase activity was determined by monitoring its decay by the immunoglobulin G heavy chain assay after the cells had been treated with several inhibitors of protein synthesis. In these experiments the kinase half-life was much longer than expected from the half-life of pp60src. The apparent contradiction between the half-lives of the kinase activity and the [35S]methionine-labeled pp60src protein could be resolved by the observation that treatment of cells with inhibitors of protein synthesis stabilized pp60src, resulting in a greatly extended half-life. Inhibitors of protein synthesis also extended the half-life of the gag precursor polypeptide, Pr76, suggesting that a host factor(s) may be required for the efficient intracellular processing of this polypeptide to the gag proteins.
D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D003513:Cycloheximide / Q000494:pharmacology; D003673:Defective Viruses / Q000378:metabolism*; D003839:Deoxyadenosines / Q000494:pharmacology; D009154:Mutation; D015688:Oncogene Protein pp60(v-src); D010770:Phosphotransferases / Q000378:metabolism*; D014176:Protein Biosynthesis; D011691:Puromycin / Q000494:pharmacology; D013696:Temperature; D014764:Viral Proteins / Q000378:metabolism*
D003839:Deoxyadenosines; D014764:Viral Proteins; D011691:Puromycin; D003513:Cycloheximide; D010770:Phosphotransferases; D015688:Oncogene Protein pp60(v-src)