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Updated: Aug 17, 2026

Assaying Protein Kinase Activity with Radiolabeled ATP
Published on: May 26, 2017
The action of PKA on smooth muscle myosin phosphorylation
1Department of Pharmacology, Dalian Medical University, 465 Zhongshan Road, Dalian 116027, PR China. xiayang9999@sina.com
Abstract:
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.
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