Modulation of an inactivating human cardiac K+ channel by protein kinase C.
Modulation of an inactivating human cardiac K+ channel by protein kinase C.
复制标题
蛋白激酶 C 对失活的人心脏 K 通道的调节。
DOI：
10.1161/01.res.75.6.999
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发表时间：
1994
影响因子：
20.1
通讯作者：
Bennett,PB
中科院分区：
文献类型：
--
作者：
Murray,KT;Fahrig,SA;Deal,KK;Po,SS;Hu,NN;Snyders,DJ;Tamkun,MM;Bennett,PB
瞬时外向电流（ITO）是心脏动作电位的重要复极化成分。在天然心肌细胞中，ITO在蛋白激酶C激活后被调节，尽管这种作用的分子本质还不清楚。最近从人心室肌克隆的通道（Kv1.4，HK 1）产生快速失活的K+电流，其与ITO的4-氨基吡啶敏感组分具有表型相似性。因此，我们研究是否也调制蛋白激酶C激活的重组通道，通过调查的影响，二酰基甘油类似物佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）对Kv1.4 K+电流表达在非洲爪蟾卵母细胞。在10 nmol/L浓度下，PMA引起双相反应，电流初始增加（14 +/-4%，平均值+/- SEM），在14分钟内达到峰值。随后在30分钟内电流显著降低（40 +/- 11%）。使用10 nmol/L PMA时，细胞膜电容没有显著变化（30分钟内下降1 +/- 1%），表明细胞膜表面积的损失不能解释K+电流的减少，尽管使用更高浓度的PMA（81 nmol/L）时细胞电容确实降低。无活性的立体异构体，4 α-PMA，对Kv1.4电流没有影响，而与蛋白激酶抑制剂staurosporine或蛋白激酶C-选择性白屈菜红碱预孵育防止PMA的影响。当使用免疫沉淀法从稳定转染的哺乳动物细胞系中纯化时，通道蛋白在体外很容易被纯化的蛋白激酶C磷酸化。（250字处删节）
The transient outward current (ITO) is an important repolarizing component of the cardiac action potential. In native cardiac myocytes, ITO is modulated after activation of protein kinase C, although the molecular nature of this effect is not well understood. A channel recently cloned from human ventricular myocardium (Kv1.4, HK1) produces a rapidly inactivating K+ current, which has phenotypic similarities to the 4-aminopyridine-sensitive component of ITO. Therefore, we examined whether this recombinant channel was also modulated by protein kinase C activation by investigating the effects of the diacylglycerol analogue phorbol 12-myristate 13-acetate (PMA) on Kv1.4 K+ current expressed in Xenopus oocytes. At a concentration of 10 nmol/L, PMA caused a biphasic response with an initial increase (14 +/- 4%, mean +/- SEM) in current, which peaked in 14 minutes. This was followed by a significant reduction (40 +/- 11%) in the current within 30 minutes. There was no significant change in cell membrane electrical capacitance with 10 nmol/L PMA (1 +/- 1% decline in 30 minutes), demonstrating that loss of cell membrane surface area did not explain the reduction in K+ current, although cell capacitance did decrease when using a higher concentration of PMA (81 nmol/L). The inactive stereoisomer, 4 alpha-PMA, had no effect on Kv1.4 current, whereas preincubation with the protein kinase inhibitor staurosporine or protein kinase C-selective chelerythrine prevented the effects of PMA. When purified from a stably transfected mammalian cell line by using immunoprecipitation, the channel protein was readily phosphorylated in vitro by purified protein kinase C.(ABSTRACT TRUNCATED AT 250 WORDS)