Cav1.1

Ca_v1.1又称为L型钙通道α1亚基（calcium channel, voltage-dependent, L type, alpha 1S subunit，CACNA1S），为一种由CACNA1S基因翻译而成的蛋白质。有时又称CACNL1A3或二氢吡啶受体（dihydropyridine receptor，DHPR）。

功能

该蛋白为骨骼肌中L型电性钙通道的五个次单元中的其中之一。该基因突变可能与低钾血周期性麻痹、甲状腺毒性周期性麻痹症，和恶性高热相关。

Ca_v1.1为骨骼肌横小管上的电压依赖性钙通道。在骨骼肌中会与肌浆网上的兰诺定受体1（RyR1）相接。当神经冲动发生时，终板电位会沿骨骼肌的细胞膜传入横小管中，并刺激Ca_v1.1。先前科学家以为当肌肉去极化时会引发钙通道开启，钙离子流入后激活RyR1，使更多钙离子从肌浆网释入细胞质，引发兴奋收缩联合作用，进而使肌肉收缩。最近研究发现在骨骼肌中（并非心肌），钙离子流入Cav1.1并非必须。Cav1.1激活后构型会改变，并与RyR1相接进行别构调节。

临床意义

在许多低钾血周期性麻痹（HOKPP）患者身上，Ca_v1.1的 domains 2 和 domains 4 有突变发生，造成其感测去极化的能力下降，激活兰诺定受体的能力下降。因此肌肉无法顺利收缩，导致患者瘫痪。此类患者会于低血钾时发生瘫痪，因胞外血钾降低会使肌肉更快回到静息电位，且会使电位更难达到阈值，使动作电位更难产生，肌肉因此无力。在Ca_v1.1缺损的患者身上，即使动作电位产生，肌浆网仍难以释放钙离子，使肌肉收缩无法完成，因此此类患者必须调整血钾浓度。相反地，若钠离子通道突变后功能增强，使肌肉长期维持去极化，则会导致高钾血周期性麻痹。

欧洲恶性高热小组（European Malignant Hyperthermia Group）将此 CACNA1S 基因的两种突变列为恶性高热的诊断之一。

阻断剂

Ca_v1.1可由二羟基吡啶阻断。

参见

• 钙通道

延伸阅读

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外部链接

• GeneReviews/NCBI/NIH/UW entry on Malignant Hyperthermia Susceptibility（页面存档备份，存于互联网档案馆）
• 医学主题词表（MeSH）：CACNA1S+protein,+human

Cav1.1引用了美国国家医学图书馆提供的数据，这些数据属于公共领域。