The action of PKA on smooth muscle myosin phosphorylation.
The aim of the study is to reveal the characterization of PKA acting on myosin. We found: (a) in the absence of Ca(2+)/CaM, PKA slightly phosphorylated MLC(20) and stimulated the Mg(2+)-ATPase activity of myosin, which was strengthened significantly by arachidonic acid (ACAD); (b) Ca(2+)-independent phosphorylation of myosin by PKA was obviously less efficient than both Ca(2+)-dependent and independent phosphorylation of myosin by MLCK; (c) micro-amount of calponin could not increase the precipitation of myosin phosphorylated by PKA, but it increased the precipitation of myosin phosphorylated by MLCK, suggesting the presence of conformational differences between the myosins phosphorylated by PKA and by MLCK.
Yang
Jing Xian
JX
Department of Pharmacology, Dalian Medical University, 465 Zhongshan Road, Dalian 116027, PR China. xiayang9999@sina.com
Lin
Yuan
Y
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000494:pharmacology; D002645:Chickens; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology*; D066298:In Vitro Techniques; D008840:Microfilament Proteins; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009218:Myosins / Q000378:metabolism*; D010766:Phosphorylation; D000096985:Calponins
D016718:Arachidonic Acid; D017301:Ca(2+) Mg(2+)-ATPase; D002135:Calcium-Binding Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D008840:Microfilament Proteins; D009219:Myosin-Light-Chain Kinase; D009218:Myosins; D000096985:Calponins