Haase H, Karczewski P, Beckert R, Krause E G
Max Delbrück Centre for Molecular Medicine, Molecular Cardiology, Berlin-Buch, Germany.
FEBS Lett. 1993 Dec 6;335(2):217-22. doi: 10.1016/0014-5793(93)80733-b.
Cyclic AMP-mediated phosphorylation of calcium channel subunits was studied in vitro and in vivo in preparations from dog heart. Calcium channels in native cardiac membranes were phosphorylated by cAMP-dependent protein kinase (PKA) solubilized with digitonin and subsequently immunoprecipitated using a polyclonal antibody generated against the deduced carboxy-terminal sequence of the cardiac beta subunit. A 62 kDa protein was identified as the major PKA-substrate in the immunoprecipitates. In the intact myocardium, this putative beta subunit was found to be phosphorylated in response to cAMP elevating agents. In contrast, no phosphorylation of a protein with an electrophoretic mobility similar to the alpha 1 subunit was detected, although 1,4-dihydropyridine receptor sites were recovered in the immunoprecipitates. Thus, we suggest that PKA-mediated phosphorylation of the beta subunit is the major mechanism for beta-adrenergic regulation of cardiac L-type calcium channel activity.
在体外和体内对犬心脏组织中钙通道亚基的环磷酸腺苷（cAMP）介导的磷酸化进行了研究。天然心肌膜中的钙通道被用洋地黄皂苷溶解的cAMP依赖性蛋白激酶（PKA）磷酸化，随后使用针对心脏β亚基推导的羧基末端序列产生的多克隆抗体进行免疫沉淀。在免疫沉淀物中，一种62 kDa的蛋白质被鉴定为主要的PKA底物。在完整的心肌中，发现这种假定的β亚基会因cAMP升高剂而发生磷酸化。相比之下，尽管在免疫沉淀物中回收了1,4-二氢吡啶受体位点，但未检测到电泳迁移率与α1亚基相似的蛋白质的磷酸化。因此，我们认为PKA介导的β亚基磷酸化是β-肾上腺素能调节心脏L型钙通道活性的主要机制。
