CAPK-phosphorylation controls the interaction of the regulatory domain of cardiac myosin binding protein C with myosin-S2 in an on-off fashion
CAPK-phosphorylation controls the interaction of the regulatory domain of cardiac myosin binding protein C with myosin-S2 in an on-off fashion
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DOI：
10.1016/s0014-5793(99)00727-9
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发表时间：
1999-06-25
期刊：
影响因子：
3.5
通讯作者：
Gautel, M
中科院分区：
文献类型：
--
作者：
Gruen, M;Prinz, H;Gautel, M
肌球蛋白结合蛋白C是横纹肌肌球蛋白丝的一种蛋白，以心肌和骨骼肌特有的同种异型表达。心肌同种异构体在心肌受到camp依赖性蛋白激酶的肾上腺素能刺激后迅速磷酸化，与肌钙蛋白- 1和磷蛋白的磷酸化一起，导致心肌因肾上腺素能刺激而呈正性肌力变性。心肌肌球蛋白结合蛋白C在与肌球蛋白s2结合的肌球蛋白结合蛋白C特异性n端区域的三个位点上被camp依赖性蛋白激酶磷酸化。这种与靠近运动结构域的肌球蛋白的相互作用可能介导了该蛋白的调节功能。心肌肌球蛋白结合蛋白C是家族性肥厚性心肌病的常见靶基因，大多数突变编码肌球蛋白结合蛋白C的n端亚片段。因此，了解n端区域的信号相互作用对于理解肌球蛋白结合蛋白C相关心肌病的病理生理非常重要。我们通过共沉淀实验和等温滴定量热法证明，肌球蛋白结合蛋白C基序的肌球蛋白-S2结合特性被camp依赖性蛋白激酶介导的三磷酸化所消除，将S2亲和力从大约5 μ M的K-d降低到无法检测的水平。我们发现慢速和快速的骨骼肌异构体不是camp依赖的蛋白激酶底物，因此这些肌球蛋白结合蛋白C异构体的S2相互作用是组成性的。因此，肌球蛋白结合蛋白C对心脏收缩性的调节似乎是一种“断裂机制”，它将释放特定的肌球蛋白头亚群，使其免受与肌球蛋白结合蛋白C基序结合所施加的空间限制。(C) 1999年欧洲生化学会联合会。
Myosin binding protein C is a protein of the myosin filaments of striated muscle which is expressed in isoforms specific for cardiac and skeletal muscle. The cardiac isoform is phosphorylated rapidly upon adrenergic stimulation of myocardium by cAMP-dependent protein kinase, and together with the phosphorylation of troponin-I and phospholamban contributes to the positive inotropy that results from adrenergic stimulation of the heart, Cardiac myosin binding protein C is phosphorylated by cAMP-dependent protein kinase on three sites in a myosin binding protein C specific N-terminal domain which binds to myosin-S2. This interaction with myosin close to the motor domain is likely to mediate the regulatory function of the protein. Cardiac myosin binding protein C is a common target gene of familial hypertrophic cardiomyopathy and most mutations encode N-terminal subfragments of myosin binding protein C. The understanding of the signalling interactions of the N-terminal region is therefore important for understanding the pathophysiology of myosin binding protein C associated cardiomyopathy. We demonstrate here by cosedimentation assays and isothermal titration calorimetry that the myosin-S2 binding properties of the myosin binding protein C motif are abolished by cAMP-dependent protein kinase-mediated trisphosphorylation, decreasing the S2 affinity from a K-d of approximate to 5 mu M to undetectable levels. We show that the slow and fast skeletal muscle isoforms are no cAMP-dependent protein kinase substrates and that the S2 interaction of these myosin binding protein C isoforms is therefore constitutively on, The regulation of cardiac contractility by myosin binding protein C therefore appears to be a 'brake-off mechanism that will free a specific subset of myosin heads from sterical constraints imposed by the binding to the myosin binding protein C motif. (C) 1999 Federation of European Biochemical Societies.