title: Tyrosylprotein kinase and phosphatase activities in membrane vesicles from normal and Rous sarcoma virus-transformed rat cells.
abstract: Membrane vesicles; isolated from normal and Rous sarcoma virus-transformed rat cells, have an associated cyclic-AMP independent kinase that phosphorylates a Mr 37,000 protein in vesicles from normal cells and proteins of Mr 37,000, 50,000, and 67,000 in vesicles from transformed cells. Proteins in vesicles from normal and transformed cells contain 9% and 77%, respectively, of their labeled phospho amino acids as phosphotyrosine. Thus, isolation of vesicles and subsequent incubation with [gamma-32P]ATP enriches the proportion of labeled phosphotyrosine in proteins (relative to other phospho amino acids) by two orders of magnitude over that found in intact cells. The in vitro phosphorylation of each of these proteins is enhanced in the presence of 10 microM Zn2+, a phosphotyrosylprotein phosphatase inhibitor. From these studies it appears that membrane vesicles may be a valuable system for examination of transformation-specific phosphorylation of proteins.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001358:Avian Sarcoma Viruses / Q000201:enzymology*; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology; D002472:Cell Transformation, Viral; D004622:Embryo, Mammalian; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism; D008970:Molecular Weight; D015688:Oncogene Protein pp60(v-src); D010749:Phosphoprotein Phosphatases / Q000235:genetics*; D010766:Phosphorylation; D011494:Protein Kinases / Q000235:genetics*; D011505:Protein-Tyrosine Kinases; D051381:Rats; D014764:Viral Proteins / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D008565:Membrane Proteins; D014764:Viral Proteins; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src); D010749:Phosphoprotein Phosphatases; D015032:Zinc