Coupling Gating with Ion Permeation in ClC Channels

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Science's STKE  24 Jun 2003:
Vol. 2003, Issue 188, pp. pe23
DOI: 10.1126/stke.2003.188.pe23

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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.

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