Anion exchangers in the red cell and beyond.

The anion exchanger genes (AE1-3) encode a family of transport proteins responsible for the electroneutral exchange of bicarbonate and chloride across membranes. These transporters are important in processes such as pH regulation and bicarbonate metabolism. This article reviews recent progress in this field based on presentations made at a satellite workshop on anion exchangers held in conjunction with the 8th Fisher Winternational Symposium on Cellular and Molecular Biology entitled "Membrane proteins in health and disease." The transmembrane topology of AE1 has been refined using various combinations of protein chemistry and site-directed mutagenesis. The use of specific inhibitors and novel expression systems continues to reveal fundamental features of the anion exchanger mechanism and its regulation. The importance of anion exchangers in blood and kidney diseases is underscored by the identification and characterization of a plethora of novel mutations in the AE1 gene. Investigations of anion exchanger structure and function have moved beyond studies of the red cell protein into the larger arenas of cellular and molecular biology.