title: Two structurally and functionally different forms of the transforming protein of PRC II avian sarcoma virus.
abstract: The primary translation product of the PRC II avian sarcoma virus genome is a protein of 105,000 daltons (P105), and we have previously shown that approximately 50% of the P105 molecules are converted to molecules of 110,000 daltons (P110) by posttranslational modification. Fractionation of PRC II-infected cells showed that P105 was contained primarily in a nonionic detergent-soluble compartment, whereas P110 partitioned almost exclusively with a nonionic detergent-insoluble or crude cytoskeletal fraction. The tyrosine-specific protein kinase activity previously observed in immunoprecipitates which presumably contained both P110 and P105 was found predominantly in the P110-containing immunoprecipitates made from the cytoskeletal fraction and was essentially absent from the P105-containing immunoprecipitates prepared from the soluble fraction. Individual analysis of 32P-labeled P110 and P105 prepared by this fractionation technique revealed that P110 contained more phosphotyrosine per mole of protein than did P105. Examination of the tryptic peptide maps of 32P-labeled P110 and P105 suggested that the additional phosphotyrosine in P110 resulted from phosphorylation at discrete sites within the protein. From these experiments, we conclude that PRC II-infected cells contain two discrete forms, P105 and P110, of the transforming protein and that each of these proteins exhibits distinct structural and functional characteristics.
mesh_terms: D001355:Alpharetrovirus / Q000378:metabolism*; D000818:Animals; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D003673:Defective Viruses / Q000378:metabolism; D015688:Oncogene Protein pp60(v-src); D010446:Peptide Fragments / Q000032:analysis; D010750:Phosphoproteins; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D010750:Phosphoproteins; D014764:Viral Proteins; D014443:Tyrosine; D011494:Protein Kinases; D015688:Oncogene Protein pp60(v-src)