Chen Tsung-Yu
Center for Neuroscience and Department of Neurology, University of California, Davis, CA 95616, USA.
Sci STKE. 2003 Jun 24;2003(188):pe23. doi: 10.1126/stke.2003.188.pe23.
In ClC chloride (Cl(-)) channels, unlike cation-selective ion channels, ion permeation is intimately coupled to fast gating. Recent research comparing the crystallographic structure of a bacterial ClC channel with functional studies of a Torpedo ClC channel suggests that gating depends on the negatively charged carboxyl group on a glutamate residue, which blocks the channel pore. In this model, the permeating Cl(-) competes with the carboxyl group for an anion-binding site in the channel pore. This model of Cl(-) competition with a glutamate gate helps explain the effect of intracellular Cl(-) on channel gating; the mechanism underlying the effects of extracellular Cl(-), however, remains to be determined, as does the nature of the Cl(-) channel slow gate.
在氯离子（Cl⁻）通道ClC中，与阳离子选择性离子通道不同，离子通透与快速门控密切相关。最近将一种细菌ClC通道的晶体结构与电鳐ClC通道的功能研究相比较的研究表明，门控取决于谷氨酸残基上带负电荷的羧基，该羧基会阻塞通道孔。在这个模型中，通透的Cl⁻与羧基竞争通道孔中的一个阴离子结合位点。这种Cl⁻与谷氨酸门控竞争的模型有助于解释细胞内Cl⁻对通道门控的影响；然而，细胞外Cl⁻作用的潜在机制以及Cl⁻通道慢门控的性质仍有待确定。
