title: Native pyrophosphate gel analysis of smooth muscle myosin phosphorylated with protein kinase C.
abstract: We have shown that the phosphorylation of smooth muscle regulatory myosin light chain (L20) with myosin light chain kinase (MLCK) produces faster moving bands (GMP1: heterodimer myosin with 1 unphosphorylated L20 and 1 mono-phosphorylated L20, GMP2: homodimer myosin with 2 mono-phosphorylated L20S) on native pyrophosphate polyacrylamide gel electrophoresis (PP1 PAGE) (J. Biochem. 100, 259-268, 1986; J. Biochem. 100, 1681-1684, 1986). However, the mobility of the myosin phosphorylated, at its L20, with protein kinase C (PK-C) was the same that of the unphosphorylated myosin (GM) on PPi PAGE. When the myosin prephosphorylated with MLCK was further phosphorylated with PK-C, PPi PAGE analysis showed only one band comigrating with GM, i.e., GMP1 and GMP2 migrated to the same position as GM. Conversely, when the myosin prephosphorylated with PK-C was further phosphorylated with MLCK, GMP1 and GMP2 were not produced. Thus the effect of L20 phosphorylated with PK-C is quite the opposite of that with MLCK, and the former predominated over the latter. We speculate that phosphorylation of L20 with PK-C "freezes" myosin in the inactive state.
authors.affiliation: Tokyo Metropolitan Institute of Medical Sciences.
authors.forename: H
authors.initials: H
authors.lastname: Takano-Ohmuro
authors.forename: K
authors.initials: K
authors.lastname: Kohama
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002147:Calmodulin / Q000494:pharmacology; D002645:Chickens; D011756:Diphosphates; D004591:Electrophoresis, Polyacrylamide Gel; D005895:Gizzard, Avian; D046911:Macromolecular Substances; D009130:Muscle, Smooth / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D013552:Swine
chemical_list: D002147:Calmodulin; D011756:Diphosphates; D046911:Macromolecular Substances; D011493:Protein Kinase C; D009219:Myosin-Light-Chain Kinase; D009218:Myosins; D002118:Calcium