title: Transformation-defective mutants of Snyder-Theilen feline sarcoma virus lack tyrosine-specific protein kinase activity.
abstract: Four phenotypically normal mink cell clones, each containing a transformation-defective provirus of the Snyder-Theilen strain of feline sarcoma virus (ST-FeSV), synthesized an 85,000-dalton viral polyprotein (P85) indistinguishable in size and antigenic complexity from that encoded by wild-type transforming ST-FeSV. An additional transformation-defective, ST-FeSV-containing flat cell clone produced a polyprotein of 88,000 daltons (P88). The viral polyproteins immunoprecipitated from cytoplasmic extracts of these cells lacked the tyrosine-specific protein kinase activity associated with the wild-type ST-FeSV gene product. In addition, the products encoded by representative transformation-defective ST-FeSV genomes were poorly phosphorylated in vivo and lacked detectable phosphotyrosine residues. Whereas proteins of ST-FeSV transformants contained elevated levels of phosphotyrosine, those of mink cells containing transformation-defective ST-FeSV exhibited phosphotyrosine levels no higher than those found in uninfected cells. These findings provide genetic evidence that the tyrosine-specific protein kinase activity associated with ST-FeSV P85 is required for virus-induced transformation.
mesh_terms: D000818:Animals; D002460:Cell Line; D002472:Cell Transformation, Viral; D005814:Genes, Viral; D008907:Mink; D009154:Mutation; D010766:Phosphorylation; D019000:Phosphotyrosine; D011494:Protein Kinases / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases; D012190:Retroviridae / Q000235:genetics*; D005253:Sarcoma Viruses, Feline / Q000201:enzymology / Q000235:genetics*; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D014764:Viral Proteins / Q000235:genetics
chemical_list: D014764:Viral Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases