nu 1, a Mr 43,000 component of postsynaptic membranes, is a protein kinase.
Acetylcholine receptor-enriched membranes from the electric organ of Torpedo californica show a major band at Mr 43,000 on NaDodSO4/polyacrylamide gels. This band is composed of three polypeptides: nu 1, nu 2, and nu 3. Polypeptide nu 1 has been found to be localized exclusively at the innervated face of the electrocyte and at the neuromuscular junction in rat muscle. We show here that monoclonal antibody to nu 1 precipitates a radioactive Mr 43,000 polypeptide from detergent-solubilized extracts of Torpedo membranes covalently labeled with periodate-oxidized [alpha-32P]ATP. The monoclonal antibody also precipitates protein kinase activity from neutralized pH 11 extracts of the acetylcholine receptor-rich membranes. These data suggest that nu 1 is a postsynaptic membrane protein kinase.
Gordon
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Milfay
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D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D029941:Fish Proteins; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D008970:Molecular Weight; D009469:Neuromuscular Junction / Q000201:enzymology*; D011494:Protein Kinases / Q000276:immunology / Q000378:metabolism*; D013570:Synaptic Membranes / Q000201:enzymology*; D014101:Torpedo
D000911:Antibodies, Monoclonal; D029941:Fish Proteins; D008565:Membrane Proteins; C049348:nu 1 protein, Torpedo; D000255:Adenosine Triphosphate; D011494:Protein Kinases