Graded activation of CRAC channel by binding of different numbers of STIM1 to Orai1 subunits
Graded activation of CRAC channel by binding of different numbers of STIM1 to Orai1 subunits
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通过不同数量的 STIM1 与 Orai1 亚基的结合分级激活 CRAC 通道
DOI：
10.1038/cr.2010.131
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发表时间：
2011-02-01
期刊：
影响因子：
44.1
通讯作者：
Xu, Tao
中科院分区：
文献类型：
--
作者：
Li, Zhengzheng;Liu, Lin;Xu, Tao
Ca2+释放激活的Ca2+ (CRAC)通道孔由Orai1形成，并在细胞内Ca2+储存耗尽后由STIM1门控。为了确定打开CRAC通道需要多少STIM1分子，我们将不同数量的Orai1亚基与STIM1的功能双串联胞质结构域（残基336-485，称为S结构域）融合。这些嵌合分子的全细胞膜片钳记录显示，在4个Orai1和8个S结构域的化学计量中，CRAC电流达到最大。进一步的实验表明，双串联S结构域特异性地与一个Orai1亚基的c端相互作用，并且随着更多的Orai1亚基与S结构域或STIM1蛋白相互作用，CRAC电流可以逐渐增加。我们的数据表明，一个CRAC通道的最大开放需要8个STIM1分子，并支持一个模型，即CRAC通道的激活不是“全有或无”的方式，而是通过结合不同数量的STIM1而经历一个渐变的过程。
The Ca2+ release-activated Ca2+ (CRAC) channel pore is formed by Orai1 and gated by STIM1 after intracellular Ca2+ store depletion. To resolve how many STIM1 molecules are required to open a CRAC channel, we fused different numbers of Orai1 subunits with functional two-tandem cytoplasmic domains of STIM1 (residues 336-485, designated as S domain). Whole-cell patch clamp recordings of these chimeric molecules revealed that CRAC current reached maximum at a stoichiometry of four Orai1 and eight S domains. Further experiments indicate that two-tandem S domains specifically interact with the C-terminus of one Orai1 subunit, and CRAC current can be gradually increased as more Orai1 subunits can interact with S domains or STIM1 proteins. Our data suggest that maximal opening of one CRAC channel requires eight STIM1 molecules, and support a model that the CRAC channel activation is not in an "all-or-none" fashion but undergoes a graded process via binding of different numbers of STIM1.