PMID:15111101
| Citation |
Dutzler, R (2004) Structural basis for ion conduction and gating in ClC chloride channels. FEBS Lett. 564:229-33 |
|---|---|
| Abstract |
Members of the ClC family of voltage-gated chloride channels are found from bacteria to mammals with a considerable degree of conservation in the membrane-inserted, pore-forming region. The crystal structures of the ClC channels of Escherichia coli and Salmonella typhimurium provide a structural framework for the entire family. The ClC channels are homodimeric proteins with an overall rhombus-like shape. Each ClC dimer has two pores each contained within a single subunit. The ClC subunit consists of two roughly repeated halves that span the membrane with opposite orientations. This antiparallel architecture defines a chloride selectivity filter within the 15-A neck of a hourglass-shaped pore. Three Cl(-) binding sites within the selectivity filter stabilize ions by interactions with alpha-helix dipoles and by chemical interactions with nitrogen atoms and hydroxyl groups of residues in the protein. The Cl(-) binding site nearest the extracellular solution can be occupied either by a Cl(-) ion or by a glutamate carboxyl group. Mutations of this glutamate residue in Torpedo ray ClC channels alter gating in electrophysiological assays. These findings reveal a form of gating in which the glutamate carboxyl group closes the pore by mimicking a Cl(-) ion. |
| Links |
PubMed Online version:10.1016/S0014-5793(04)00210-8 |
| Keywords |
Amino Acid Sequence; Animals; Chloride Channels/chemistry; Chloride Channels/metabolism; Chlorides/metabolism; Ion Channel Gating/physiology; Models, Molecular; Molecular Sequence Data; Potassium Channels/chemistry; Potassium Channels/metabolism; Protein Conformation; Sequence Alignment |
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