title: Calcium-calmodulin-dependent myosin phosphorylation by pancreatic islets.
abstract: Pancreatic islets contain enzyme activity which catalyzes the phosphorylation by MgATP of cardiac, skeletal, or smooth muscle myosin light chains. The enzyme is activated by calcium (Ka = 10 microM) and calmodulin (Ka = 2 nM) and inhibited by trifluoperazine (Ki = 10 microM), a known inhibitor of calmodulin and of insulin secretion. The enzyme binds to a calmodulin affinity column when Ca2+ is present and is eluted when Ca2+ is omitted. These are the properties of myosin light chain kinase. Since phosphorylation of smooth muscle myosin is necessary for its activation by actin, the kinase may have a key role in coupling stimuli that increase intracellular calcium to the contractile processes involved in insulin secretion.
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D009132:Muscles / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D002135:Calcium-Binding Proteins; D002147:Calmodulin; D047428:Protein Kinase Inhibitors; D014268:Trifluoperazine; D010770:Phosphotransferases; D011494:Protein Kinases; D009219:Myosin-Light-Chain Kinase; D002118:Calcium