title: Enzymatically inactive p60c-src mutant with altered ATP-binding site is fully phosphorylated in its carboxy-terminal regulatory region.
abstract: Cellular src protein, p60c-src, is phosphorylated on tyrosine 527 in chicken embryo fibroblasts, and this phosphorylation is implicated in suppressing the protein-tyrosine kinase activity and transforming potential of p60c-src. To determine whether tyrosine 527 phosphorylation is dependent on p60c-src kinase activity, the ATP-binding site of chicken p60c-src was destroyed by substitution of lysine 295 with methionine. The resultant protein, p60c-src(M295), expressed either in chicken cells or in yeast, lacked detectable kinase activity. Nevertheless, tyrosine and serine phosphorylation of p60c-src(M295) overproduced in chicken cells were indistinguishable from that of authentic p60c-src. By contrast, p60c-src(M295) was not phosphorylated on tyrosine in yeast. These results suggest that a protein kinase present in chicken cells but not in yeast phosphorylates tyrosine 527 in trans, and are consistent with the possibility that this kinase is distinct from p60c-src.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000495:Allosteric Site; D000818:Animals; D002645:Chickens / Q000235:genetics; D005347:Fibroblasts / Q000201:enzymology; D010766:Phosphorylation; D019000:Phosphotyrosine; D011494:Protein Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src); D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014443:Tyrosine / Q000031:analogs & derivatives / Q000502:physiology
chemical_list: D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src)