Molecular characterization of the cation-chloride cotransporter family.

Na-K-2Cl cotransporters, Na-Cl cotransporters and K-Cl cotransporters have recently been shown to constitute a new gene family of membrane transport proteins. At least five distinct members of this family of cation-chloride cotransporters have been found in vertebrates and several as yet functionally uncharacterized sequences have been identified in insects, worms and yeast. The relationships among the various known members of this gene family is briefly reviewed along with our current knowledge about the topological structure of these proteins in the plasma membrane.