Cav1.1

Ca_v1.1又稱為L型鈣通道α1亞基（calcium channel, voltage-dependent, L type, alpha 1S subunit，CACNA1S），為一種由CACNA1S基因轉譯而成的蛋白質。有時又稱CACNL1A3或二氫吡啶受體（dihydropyridine receptor，DHPR）。

功能

該蛋白為骨骼肌中L型電性鈣通道的五個次單元中的其中之一。該基因突變可能與低鉀血周期性麻痺、甲狀腺毒性週期性麻痺症，和惡性高熱相關。

Ca_v1.1為骨骼肌横小管上的電壓依賴性鈣通道。在骨骼肌中會與肌漿網上的蘭諾定受體1（RyR1）相接。當神經衝動發生時，終板電位會沿骨骼肌的細胞膜傳入橫小管中，並刺激Ca_v1.1。先前科學家以為當肌肉去極化時會引發鈣通道開啟，鈣離子流入後活化RyR1，使更多鈣離子從肌漿網釋入細胞質，引發興奮收縮聯合作用，進而使肌肉收縮。最近研究發現在骨骼肌中（並非心肌），鈣離子流入Cav1.1並非必須。Cav1.1活化後構型會改變，並與RyR1相接進行別構調節。

臨床意義

在許多低鉀血周期性麻痺（HOKPP）患者身上，Ca_v1.1的 domains 2 和 domains 4 有突變發生，造成其感測去極化的能力下降，活化蘭諾定受體的能力下降。因此肌肉無法順利收縮，導致患者癱瘓。此類患者會於低血鉀時發生癱瘓，因胞外血鉀降低會使肌肉更快回到静息电位，且會使電位更難達到閾值，使動作電位更難產生，肌肉因此無力。在Ca_v1.1缺損的患者身上，即使動作電位產生，肌漿網仍難以釋放鈣離子，使肌肉收縮無法完成，因此此類患者必須調整血鉀濃度。相反地，若鈉離子通道突變後功能增強，使肌肉長期維持去極化，則會導致高鉀血周期性麻痺。

歐洲惡性高熱小組（European Malignant Hyperthermia Group）將此 CACNA1S 基因的兩種突變列為惡性高熱的診斷之一。

阻斷劑

Ca_v1.1可由二羥基吡啶阻斷。

參見

• 钙通道

延伸閱讀

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外部連結

• GeneReviews/NCBI/NIH/UW entry on Malignant Hyperthermia Susceptibility（页面存档备份，存于互联网档案馆）
• 醫學主題詞表（MeSH）：CACNA1S+protein,+human

Cav1.1引用了美国国家医学图书馆提供的資料，这些資料属于公共领域。