Iwasa Y, Hosey M M
J Biol Chem. 1984 Jan 10;259(1):534-40.
Cardiac sarcolemma proteins were phosphorylated by exogenous Ca2+-activated phospholipid-dependent protein kinase (protein kinase C). The phosphorylation reactions were absolutely dependent on the simultaneous presence of Ca2+ and phosphatidylserine. Phosphatidylethanolamine, phosphatidylcholine, phosphatidylinositol, sphingomyelin, and phosphatidic acid were ineffective in supporting protein kinase C-catalyzed membrane phosphorylation. The reactions were not stimulated by diolein. In contrast, diolein inhibited phosphatidylserine-stimulated phosphorylation at all calcium concentrations tested. The major substrates for protein kinase C in cardiac membranes were peptides of 88,000, 51,000, 42,000 daltons, and the peptide known as phospholamban (Mr = 27,000 or 11,000 depending on sample preparation). Phosphorylation of phospholamban by protein kinase C was additive with that catalyzed by membrane-bound or exogenous cyclic AMP-dependent protein kinase and with Ca2+-calmodulin-dependent protein kinase. The results suggest that protein kinase C might have a role in the regulation of cardiac membrane phosphorylation by beta-adrenergic and muscarinic cholinergic agonists.
心脏肌膜蛋白可被外源性Ca2+激活的磷脂依赖性蛋白激酶（蛋白激酶C）磷酸化。磷酸化反应绝对依赖于Ca2+和磷脂酰丝氨酸的同时存在。磷脂酰乙醇胺、磷脂酰胆碱、磷脂酰肌醇、鞘磷脂和磷脂酸在支持蛋白激酶C催化的膜磷酸化方面无效。二油精不能刺激该反应。相反，在所有测试的钙浓度下，二油精均抑制磷脂酰丝氨酸刺激的磷酸化。心脏膜中蛋白激酶C的主要底物是88,000、51,000、42,000道尔顿的肽，以及被称为受磷蛋白的肽（分子量为27,000或11,000，取决于样品制备）。蛋白激酶C对受磷蛋白的磷酸化与膜结合的或外源性环磷酸腺苷依赖性蛋白激酶以及Ca2+ - 钙调蛋白依赖性蛋白激酶催化的磷酸化具有加和性。结果表明，蛋白激酶C可能在β - 肾上腺素能和毒蕈碱胆碱能激动剂对心脏膜磷酸化的调节中发挥作用。
