title: A tyrosine kinase related to pp60c-src is associated with membranes of Electrophorus electricus electric organ.
abstract: A tyrosine-specific protein kinase immunologically related to pp60c-src, the cellular homolog of the Rous sarcoma virus-transforming protein, was expressed at elevated levels in the electric organ of the electric eel Electrophorus electricus. The electric organ kinase phosphorylated antibodies reactive with pp60c-src at tyrosine residues in immune complex protein kinase assays and was associated with electric organ membranes enriched in acetylcholine receptors. The protein recognized by anti-pp60c-src antibodies was phosphorylated in endogenous membrane phosphorylation reactions and was shown to have a relative molecular mass of 57 kDa by two-dimensional gel electrophoresis. In immune complex protein kinase assays the 57-kDa protein was phosphorylated at threonine by a distinct threonine kinase from the electric organ. The tyrosine kinase was purified 844-fold from electric organ membranes by chromatography on omega-aminohexyl agarose, phosphocellulose, and casein-Sepharose. Threonine kinase activity in immunoprecipitates was not observed in the tyrosine kinase fractions after the first step. Incubation of the casein Sepharose fraction with [gamma-32P]ATP-Mn2+ in solution resulted in phosphorylation of only the 57-kDa protein. Phosphorylation occurred solely at tyrosine, suggesting that the kinase is capable of autophosphorylation. The structural and functional properties of the 57-kDa electric organ kinase indicate that the 57-kDa electric organ protein is a member of the src subfamily of tyrosine kinases and is closely related to pp60c-src.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D001358:Avian Sarcoma Viruses / Q000201:enzymology; D002462:Cell Membrane / Q000201:enzymology; D004557:Electric Organ / Q000201:enzymology*; D004593:Electrophorus; D007074:Immunoglobulin G; D008970:Molecular Weight; D015688:Oncogene Protein pp60(v-src); D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D012191:Retroviridae Proteins / Q000276:immunology / Q000378:metabolism*; D014018:Tissue Distribution
chemical_list: D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D012191:Retroviridae Proteins; D011505:Protein-Tyrosine Kinases; D015688:Oncogene Protein pp60(v-src)