Molecular identification of a volume-regulated chloride channel
Molecular identification of a volume-regulated chloride channel
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DOI：
10.1038/37151
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发表时间：
1997-11-27
期刊：
影响因子：
64.8
通讯作者：
Horowitz, B
中科院分区：
文献类型：
--
作者：
Duan, D;Winter, C;Horowitz, B
体积调节的氯离子电流（I-Cl.vol）普遍存在于哺乳动物细胞中，并且是调节电活性细胞体积、细胞内pH、免疫应答、细胞增殖和分化所必需的。然而，负责I-Cl.vol的分子尚未确定（1-3）。尽管已经提出从克隆基因表达的三种假定的氯离子通道蛋白（P-糖蛋白（4）、pI（Cln）（参考文献5）和ClC-2（参考文献6））是I-Cl.vol的分子等价物，但认为P-糖蛋白和pI（Cln）都不是氯离子通道或其部分（7，8），并且表达的ClC-2通道的性质不同于天然I-Cl.vol（参考文献6）。3、6）。在此，我们报道了CIC家族的另一个成员ClC-3的心脏克隆在NIH/3 T3细胞中的功能性表达，导致了大的基础活性氯离子传导，其受到细胞体积的强烈调节，并表现出许多与天然细胞中I-Cl.vol相同的性质（1- 3，9 -13）。在ClC-3跨膜结构域末端的579位天冬酰胺突变为赖氨酸，消除了向外整流，并将阴离子选择性从I- > Cl-改变为Cl- > I-，但保持溶胀活化不变。由于ClC-3是属于氯离子通道大基因家族的通道蛋白（3，14），这些结果表明ClC-3在许多天然哺乳动物细胞中编码I-Cl.vol。
A volume-regulated chloride current (I-Cl.vol) is ubiquitously present in mammalian cells, and is required for the regulation of electrical activity cell volume, intracellular pH, immunological responses, cell proliferation and differentiation. However, the molecule responsible for I-Cl.vol has yet to be determined(1-3). Although three putative chloride channel proteins expressed from cloned genes (P-glycoprotein(4), pI(Cln), (ref. 5) and ClC-2 (ref. 6)) have been proposed to be the molecular equivalent of I-Cl.vol, neither P-glycoprotein nor pI(Cln), is thought to be a chloride channel or part thereof(7,8), and the properties of expressed ClC-2 channels differ from native I-Cl.vol (refs. 3, 6). Here we report that functional expression in NIH/3T3 cells of a cardiac clone of another member of the CIC family, ClC-3, results in a large basally active chloride conductance, which is strongly modulated by cell volume and exhibits many properties identical to those of I-Cl.vol in native cells(1-3,9-13). A mutation of asparagine to lysine at position 579 at the end of the transmembrane domains of ClC-3 abolishes the outward rectification and changes the anion selectivity from I- > Cl- to Cl- > I- but leaves swelling activation intact. Because ClC-3 is a channel protein belonging to a large gene family of chloride channels(3,14), these results indicate that ClC-3 encodes I-Cl.vol in many native mammalian cells.