title: Protein kinase C phosphorylates pp60src at a novel site.
abstract: The transforming protein of Rous sarcoma virus (pp60v-src) and its normal cellular homolog (pp60c-src) are demonstrated to be phosphorylated at serine 12 in vivo under certain conditions. We propose that protein kinase C is responsible for this modification based on the following evidence. First, the tumor promoters, 12-O-tetradecanoylphorbol-13-acetate and teleocidin, and synthetic diacylglycerol, known activators of protein kinase C in vivo, cause nearly complete phosphorylation of pp60src at serine 12. Second, among five purified serine/threonine-specific protein kinases tested, only protein kinase C phosphorylates pp60c-src and pp60v-src in vitro at serine 12. Third, purified protein kinase C phosphorylates a synthetic peptide corresponding to the N-terminal 20 amino acids of pp60c-src at serine 12. The physiological significance of this novel phosphorylation is discussed.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001358:Avian Sarcoma Viruses / Q000201:enzymology; D001921:Brain / Q000201:enzymology; D002478:Cells, Cultured; D007700:Kinetics; D051379:Mice; D009132:Muscles / Q000201:enzymology; D015688:Oncogene Protein pp60(v-src); D010766:Phosphorylation; D011493:Protein Kinase C / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D012191:Retroviridae Proteins / Q000378:metabolism*; D012694:Serine; D013379:Substrate Specificity; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
chemical_list: D012191:Retroviridae Proteins; D012694:Serine; D011494:Protein Kinases; D015688:Oncogene Protein pp60(v-src); D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate