Maintaining homeostasis of Ca2+stores in theendoplasmic reticulum (ER) is crucial for properCa2+signaling and key cellular functions. The Ca2+-release-activated Ca2+(CRAC) channel is respon-sible for Ca2+influx and refilling after store depletion,but how cells cope with excess Ca2+when ER storesare overloaded is unclear. We show that TMCO1 is anER transmembrane protein that actively preventsCa2+stores from overfilling, acting as what we terma ‘‘Ca2+load-activated Ca2+channel’’ or ‘‘CLAC’’channel. TMCO1 undergoes reversible homotetra-merization in response to ER Ca2+overloadingand disassembly upon Ca2+depletion and forms aCa2+-selective ion channel on giant liposomes.TMCO1 knockout mice reproduce the main clinicalfeatures of human cerebrofaciothoracic (CFT)dysplasia spectrum, a developmental disorder linkedto TMCO1 dysfunction, and exhibit severe mishan-dling of ER Ca2+in cells. Our findings indicate thatTMCO1 provides a protective mechanism to preventoverfilling of ER stores with Ca2+ions
Wang, Qiao-Chu; Zheng, Qiaoxia; Tan, Haiyan; Zhang, Bing; Li, Xiaoling; Yang, Yuxiu; Yu, Jie; Liu, Yang; Chai, Hao; Wang, Xi; Sun, Zhongshuai; Wang, Jiu-Qiang; Zhu, Shu; Wang, Fengli; Yang, Maojun; Guo, Caixia; Wang, Heng; Zheng, Qingyin; Li, Yang; Chen, Quan; Zhou, Aimin; and Tang, Tie-Shan, "TMCO1 Is an ER Ca2+ Load-Activated Ca2+ Channel" (2016). Chemistry Faculty Publications. 535.
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