The relationship between calmodulin binding and phosphorylation of smooth muscle myosin kinase by the catalytic subunit of 3':5' cAMP-dependent protein kinase.
The relationship between calmodulin binding and phosphorylation of smooth muscle myosin kinase by the catalytic subunit of 3':5' cAMP-dependent protein kinase.
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钙调蛋白结合与 3:5 cAMP 依赖性蛋白激酶催化亚基磷酸化平滑肌肌球蛋白激酶之间的关系。
DOI：
10.1016/s0021-9258(19)69586-4
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
Adelstein
中科院分区：
文献类型：
--
作者：
Anne Conti;Adelstein
平滑肌肌球蛋白轻链激酶，一种钙调蛋白依赖性酶，在钙存在下结合1摩尔钙调蛋白/摩尔激酶（Adelstein，R.美国，和Klee，C. B。（1981）J.Biol.Chem.256，出版中。这种酶是cAMP依赖性蛋白激酶的底物，无论钙调蛋白是否结合。当钙调蛋白不与肌球蛋白激酶结合时，蛋白激酶将磷酸盐掺入肌球蛋白激酶的两个位点。在这种情况下，磷酸化显著降低肌球蛋白激酶活性的速率。肌球蛋白激酶活性的降低是由于50%激酶活性激活所需的钙调蛋白量增加了10-20倍。磷酸化对肌球蛋白激酶活性的影响可以通过使用纯化的磷酸酶去磷酸化来逆转（Pato，M. D、和Adelstein，R. S.（1980）J.Biol.Chem.255，6535-6538）。当钙调蛋白与肌球蛋白激酶结合时，磷酸盐被掺入单个位点，对肌球蛋白激酶活性没有影响。通过变性肌球蛋白激酶的胰蛋白酶消化证实了肌球蛋白激酶中至少两个可以磷酸化的位点的存在。
Smooth muscle myosin light chain kinase, a calmodulin-dependent enzyme, binds 1 mol of calmodulin/mol of kinase in the presence of calcium (Adelstein, R. S., and Klee, C. B. (1981) J. Biol. Chem. 256, in press. This enzyme is a substrate for cAMP-dependent protein kinase whether or not calmodulin is bound. When calmodulin is not bound to myosin kinase, protein kinase incorporates phosphate into two sites in myosin kinase. Under these circumstances, phosphorylation markedly lowers the rate of myosin kinase activity. The decrease in myosin kinase activity is due to a 10-20-fold increase in the amount of calmodulin necessary for 50% activation of kinase activity. The effect of phosphorylation on the activity of myosin kinase can be reversed by dephosphorylation using a purified phosphatase (Pato, M. D., and Adelstein, R. S. (1980) J. Biol. Chem. 255, 6535-6538) isolated from smooth muscle. When calmodulin is bound to myosin kinase, phosphate is incorporated into a single site with no effect on myosin kinase activity. The presence of at least two sites that can be phosphorylated in myosin kinase was confirmed by tryptic digestion of denatured myosin kinase.