Dutzler Raimund
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Trends Neurosci. 2004 Jun;27(6):315-20. doi: 10.1016/j.tins.2004.04.001.
ClC channels constitute a large family of Cl(-)-selective ion channels that are present in diverse organisms. The channels have a complex gating behavior, in which channel opening and closing is tightly coupled to ion permeation. Recent success in the structure determination of bacterial channels has revealed the overall architecture of this family and provided important insight into ion selectivity and gating. The ClC channels are homodimers, with each subunit containing an ion conduction pore. In the narrow selectivity filter of each pore, Cl(-) are bound to several sites through electrostatic interactions with helix dipoles and the partial charges of protein residues. In the closed conformation of the channel, a conserved glutamate residue occupies one of the ion-binding sites; on channel opening, this glutamate residue moves out of the binding site, thereby making room for an additional Cl(-) ion.
氯离子通道构成了一个庞大的氯离子选择性离子通道家族,存在于多种生物体中。这些通道具有复杂的门控行为,其中通道的开放和关闭与离子通透紧密耦合。最近在细菌通道结构测定方面取得的成功揭示了该家族的整体结构,并为离子选择性和门控提供了重要见解。氯离子通道是同型二聚体,每个亚基都包含一个离子传导孔。在每个孔的狭窄选择性过滤器中,氯离子通过与螺旋偶极子和蛋白质残基的部分电荷的静电相互作用与多个位点结合。在通道的关闭构象中,一个保守的谷氨酸残基占据其中一个离子结合位点;通道开放时,这个谷氨酸残基从结合位点移出,从而为额外的氯离子腾出空间。