Synergistic phosphorylation of rabbit muscle glycogen synthase by cyclic AMP-dependent protein kinase and casein kinase I. Implications for hormonal regulation of glycogen synthase.
Synergistic phosphorylation of rabbit muscle glycogen synthase by cyclic AMP-dependent protein kinase and casein kinase I. Implications for hormonal regulation of glycogen synthase.
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DOI：
10.1016/s0021-9258(18)60501-0
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发表时间：
1989-06
期刊：
影响因子：
--
通讯作者：
H. Flotow;P. Roach
中科院分区：
文献类型：
--
作者：
H. Flotow;P. Roach
兔骨骼肌糖原合酶的磷酸化酪蛋白激酶I显着增强，如果酶已被磷酸化cAMP依赖性蛋白激酶。磷酸盐存在于主要cAMP依赖性蛋白激酶位点，位点1a、1b和2（丝氨酸7），增加了酪蛋白激酶I对这些位点附近残基的活性。这种协同磷酸化与糖原合酶的有效失活相关。对该酶亚基的NH 2末端的分析表明，丝氨酸7的磷酸化导致丝氨酸10成为酪蛋白激酶I的优选位点，并且磷酸丝氨酸可能是酪蛋白激酶I的重要识别决定簇。这一发现也可以解释肾上腺素刺激骨骼肌如何引起丝氨酸残基磷酸化状态的显著增加，特别是丝氨酸10，不被cAMP依赖性蛋白激酶识别。
The phosphorylation of rabbit skeletal muscle glycogen synthase by casein kinase I is markedly enhanced if the enzyme has previously been phosphorylated by cAMP-dependent protein kinase. The presence of phosphate in the primary cAMP-dependent protein kinase sites, sites 1a, 1b, and 2 (serine 7), increases the activity of casein kinase I toward residues in the vicinity of these sites. This synergistic phosphorylation correlates with potent inactivation of the glycogen synthase. Analysis of the NH2terminus of the enzyme subunit indicated that phosphorylation at serine 7 caused serine 10 to become a preferred casein kinase I site and that phosphoserine can be an important recognition determinant for casein kinase I. This finding can also explain how epinephrine stimulation of skeletal muscle provokes significant increases in the phosphorylation state of serine residues, in particular serine 10, not recognized by cAMP-dependent protein kinase.