Actin Activation of Phosphorylated Aortic Myosin
The interaction of actin and myosin in smooth muscle, like that in striated muscle, is controlled through changes in the intracellular calcium concentration. The calcium-sensitive mechanism responsible for the primary regulation in smooth muscle occurs through phosphorylation of myosin light chain (Barron et al., 1980; Hathaway and Adelstein, 1979; Sherry et al., 1978). The investigators cited have shown that myosin phosphorylation is prerequisite to actin activation of the MgATPase. A secondary modulation of myosin MgATPase by calcium was first reported by Chacko et al (1977). This group showed that direct interaction of calcium with phosphorylated myosin from vas deferens increased the MgATPase activity to a level higher than that observed in the absence of calcium. Similar findings for phosphorylated myosin from vascular smooth muscle were reported by Rees and Frederiksen (1981).
KeywordsMyosin Light Chain Myosin Light Chain Kinase Secondary Modulation Myosin Phosphorylation Actin Concentration
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