Ion permeation and selectivity in ClC-type chloride channels

Voltage-gated anion channels are present in almost every living cell and ha ve many physiological functions. Recently, a novel gene family encoding vol tage-gated chloride channels, the ClC family, was identified. The knowledge of primary amino acid sequences has allowed for the study of these anion c hannels in heterologous expression systems and made possible the combinatio n of site-directed mutagenesis and high-resolution electrophysiological mea surements as a means of gaining insights into the molecular basis of channe l function. This review focuses on one particular aspect of chloride channe l function, the selective transport of anions through biological membranes. I will describe recent experiments using a combination of cellular electro physiology, molecular genetics, and recombinant DNA technology to study the molecular basis of ion permeation and selection in ClC-type chloride chann els. These novel tools have provided new insights into basic mechanisms und erlying the function of these biologically important channels.