VOLTAGE-DEPENDENT POTENTIATION OF THE ACTIVITY OF CARDIAC L-TYPE CALCIUM CHANNEL-ALPHA-1 SUBUNITS DUE TO PHOSPHORYLATION BY CAMP-DEPENDENT PROTEIN-KINASE
VOLTAGE-DEPENDENT POTENTIATION OF THE ACTIVITY OF CARDIAC L-TYPE CALCIUM CHANNEL-ALPHA-1 SUBUNITS DUE TO PHOSPHORYLATION BY CAMP-DEPENDENT PROTEIN-KINASE
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DOI：
10.1073/pnas.90.21.10135
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发表时间：
1993-11-01
影响因子：
11.1
通讯作者：
CATTERALL, WA
中科院分区：
文献类型：
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作者：
SCULPTOREANU, A;ROTMAN, E;CATTERALL, WA
在用cAMP依赖性蛋白激酶的催化亚基透析细胞期间，由中国仓鼠卵巢（CHO）细胞中表达的心脏L型Ca通道的α 1亚基介导的钡电流增加至10倍。外源性激酶部分激活后，α 1亚基的活性也可逆地增强高达3.5倍的预脉冲电压范围为0至+150 mV。在+48 mV下，以双相时程产生增强，时间常数为131 ms和8 s。在-60 mV下的反射是双相的，半衰期为12 ms和100 ms，并且在磷酸酶抑制剂冈田酸的存在下被阻断。在透析过程中的激酶和电压依赖性增强的钙通道活性的增加都伴随着电压依赖性的激活更负的膜电位的变化。由于蛋白质磷酸化和二氢吡啶钙通道激动剂Bay K8644，Ba电流增加约为加性。结果表明，心脏L型钙通道的α 1亚基足以通过cAMP依赖性蛋白激酶对钙通道活性进行实质性调节，并通过状态依赖性蛋白磷酸化进行增强。α 1亚基活性的电压依赖性增强可能有助于响应于增加的刺激速率而增加收缩力，即心肌中的正阶梯效应。
Barium currents mediated by the alpha1 subunit of the cardiac L-type Ca channel expressed in Chinese hamster ovary (CHO) cells were increased up to 10-fold during dialysis of the cell with the catalytic subunit of cAMP-dependent protein kinase. After partial activation by exogenous kinase, the activity of the alpha1 subunit was also reversibly potentiated up to 3.5-fold by prepulses to voltages in the range of 0 to +150 mV. Potentiation at +48 mV developed with a biphasic time course with time constants of 131 ms and 8 s. Reversal at -60 mV was biphasic with half-times of 12 ms and 100 ms and was blocked in the presence of the phosphatase inhibitor okadaic acid. Both the increase in calcium-channel activity during dialysis with kinase and the voltage-dependent potentiation were accompanied by shifts in the voltage dependence of activation to more negative membrane potentials. The increases in Ba current due to protein phosphorylation and to the dihydropyridine Ca channel agonist Bay K8644 were approximately additive. The results show that the al subunit of the cardiac L-type Ca channel is sufficient for substantial modulation of Ca-channel activity by cAMP-dependent protein kinase and for potentiation by state-dependent protein phosphorylation. Voltage-dependent potentiation of the activity of the alpha1 subunit may contribute to the increase in contractile force in response to increased rate of stimulation, the positive staircase effect in heart muscle.