Heterogeneity of anion exchangers mediating chloride transport in the proximal tubule.
Three distinct anion exchangers are described that directly or indirectly mediate Cl- transport across the luminal membrane of the proximal tubule cell. Studies on the intact proximal tubule indicate that the Cl(-)-formate exchanger is a major mechanism for Cl- transport under physiologic conditions. As just discussed, the physiologic importance of the Cl(-)-oxalate and SO4 = (oxalate)-CO3 = exchangers mediating Cl- transport across the luminal membrane of the proximal tubule cell is currently unknown. These three anion exchangers are part of a larger group of at least eight distinct anion transporters in the proximal tubule that share with erythrocyte Band 3 the properties of stilbene sensitivity and/or the ability to mediate anion exchange. It is tempting to speculate that these proximal tubule anion transporters are members of a family of proteins structurally related to the prototypic anion exchanger, erythrocyte Band 3. If this is true, comparing the structures of these anion transporters with each other and with Band 3 should provide important insight into the molecular basis for differences in substrate and inhibitor specificity within this family of transport proteins.
Aronson
P S
PS
Department of Medicine, Yale University School of Medicine, New Haven, Connecticut 06510.
Kuo
S M
SM
D000818:Animals; D002254:Carbonates / Q000378:metabolism; D002352:Carrier Proteins / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism*; D005561:Formates / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D010070:Oxalates / Q000378:metabolism; D019815:Oxalic Acid; D011817:Rabbits; D013431:Sulfates / Q000378:metabolism
D002254:Carbonates; D002352:Carrier Proteins; D002712:Chlorides; D005561:Formates; D010070:Oxalates; D013431:Sulfates; C030544:formic acid; D019815:Oxalic Acid