THE ELECTRONEUTRAL CATION-CHLORIDE COTRANSPORTERS

Electroneutral cation-chloride cotransporters are widely expressed and perform a variety of physiological roles. A novel gene family of five members, encompassing a Na+-Cl- transporter, two Na+-K+-2Cl(-) transp orters and two K+-Cl- cotransporters, encodes these membrane proteins; homologous genes have also been identified in a prokaryote and a numb er of lower eukaryotes. The cotransporter proteins share a common pred icted membrane topology, with twelve putative transmembrane segments f lanked by long hydrophilic N- and C-terminal cytoplasmic domains. The molecular identification of these transporters has had a significant i mpact on the study of their function, regulation and pathophysiology.