Cell transformation by pp60c-src mutated in the carboxy-terminal regulatory domain.
We introduced two mutations into the carboxy-terminal regulatory region of chicken pp60c-src. One, F527, replaces tyrosine 527 with phenylalanine. The other, Am517, produces a truncated pp60c-src protein lacking the 17 carboxy-terminal amino acids. Both mutant proteins were phosphorylated at tyrosine 416 in vivo. The specific activity of the Am517 mutant protein kinase was similar to that of wild-type pp60c-src whereas that of the F527 mutant was 5- to 10-fold higher. Both mutant c-src genes induced focus formation on NIH 3T3 cells, but the foci appeared at lower frequency, and were smaller than foci induced by polyoma middle tumor antigen (mT). The wild-type or F527 pp60c-src formed a complex with mT, whereas the Am517 pp60c-src did not. The results suggest that one, inability to phosphorylate tyrosine 527 increases pp60c-src protein kinase activity and transforming ability; two, transformation by mT involves other events besides lack of phosphorylation at tyrosine 527 of pp60c-src; three, activation of the pp60c-src protein kinase may not be required for transformation by the Am517 mutant; and four, the carboxyl terminus of pp60c-src appears to be required for association with mT.
D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D005796:Genes; D005809:Genes, Regulator; D005814:Genes, Viral; D051379:Mice; D008815:Mice, Inbred Strains; D009154:Mutation; D015688:Oncogene Protein pp60(v-src); D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D012190:Retroviridae / Q000235:genetics; D012191:Retroviridae Proteins / Q000235:genetics*
D012191:Retroviridae Proteins; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src)