钙调蛋白的 N-和 C 结构域都需要 Ca2+来调节 CaV1.2 钙通道。
Both N- and C-lobes of calmodulin are required for Ca2+-dependent regulations of CaV1.2 Ca2+ channels.
机构信息
Department of Pharmaceutical Toxicology, School of Pharmaceutical Sciences, China Medical University, 92 Beier Road, Shenyang 110001, China.
出版信息
Biochem Biophys Res Commun. 2010 Jan 8;391(2):1170-6. doi: 10.1016/j.bbrc.2009.11.171. Epub 2009 Dec 16.
We investigated the concentration- and Ca(2+)-dependent effects of CaM mutants, CaM(12) and CaM(34), in which Ca(2+)-binding to its N- and C-lobes was eliminated, respectively, on the Ca(V)1.2 Ca(2+) channel by inside-out patch clamp in guinea-pig cardiomyocytes. Both CaM(12) and CaM(34) (0.7-10muM) applied with 3mM ATP produced channel activity after "rundown". Concentration-response curves were bell-shaped, similar to that for wild-type CaM. However, there was no obvious leftward shift of the curves by increasing [Ca(2+)], suggesting that both functional lobes of CaM were necessary for the Ca(2+)-dependent shift. However, channel activity induced by the CaM mutants showed Ca(2+)-dependent decrease, implying a Ca(2+) sensor existing besides CaM. These results suggest that both N- and C-lobes of CaM are required for the Ca(2+)-dependent regulations of Ca(V)1.2 Ca(2+) channels.
我们通过豚鼠心肌细胞的内面向外膜片钳技术，研究了分别缺失 CaM 的 N 端和 C 端钙离子结合位点的 CaM(12)和 CaM(34)突变体，在浓度和钙离子依赖的条件下，对 Ca(V)1.2 钙离子通道的作用。在“耗尽”后，用 3mMATP 处理 CaM(12)和 CaM(34)(0.7-10μM)均可产生通道活性。浓度反应曲线呈钟形，与野生型 CaM 的曲线相似。然而，增加[Ca(2+)]并没有明显使曲线向左移位，表明 CaM 的两个功能结构域对于钙离子依赖性移位都是必需的。然而，CaM 突变体诱导的通道活性表现出钙离子依赖性的降低，暗示除了 CaM 之外还存在钙离子感受器。这些结果表明，CaM 的 N 端和 C 端对于 Ca(V)1.2 钙离子通道的钙离子依赖调节都是必需的。
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