Referenced in: none

Automatically associated channels: ClC1 , ClC4

Title: Ion-binding properties of the ClC chloride selectivity filter.

Authors: Séverine Lobet, Raimund Dutzler

Journal, date & volume: EMBO J., 2006 Jan 11 , 25, 24-33

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/16341087

Abstract
The ClC channels are members of a large protein family of chloride (Cl-) channels and secondary active Cl- transporters. Despite their diverse functions, the transmembrane architecture within the family is conserved. Here we present a crystallographic study on the ion-binding properties of the ClC selectivity filter in the close homolog from Escherichia coli (EcClC). The ClC selectivity filter contains three ion-binding sites that bridge the extra- and intracellular solutions. The sites bind Cl- ions with mM affinity. Despite their close proximity within the filter, the three sites can be occupied simultaneously. The ion-binding properties are found conserved from the bacterial transporter EcClC to the human Cl- channel ClC-1, suggesting a close functional link between ion permeation in the channels and active transport in the transporters. In resemblance to K+ channels, ions permeate the ClC channel in a single file, with mutual repulsion between the ions fostering rapid conduction.