Molecular characterization of the murine Slc26a6 anion exchanger: functional comparison with Slc26a1

We report the molecular and functional characterization of murine Slc26a6, the putative apical chloride-formate exchanger of the proximal tubule. The Slc26a6 transcript is expressed in several tissues, including kidney. Alternative splicing of the second exon generates two distinct isoforms, denoted Slc26a6a and Slc26a6b, which differ in the inclusion of a 23-residue NH2-terminal extension. Functional comparison with murine Slc26a1, the basolateral oxalate exchanger of the proximal tubule, reveals a number of intriguing differences. Whereas Slc26a6 is capable of Cl−, SO 4 2 − , formate, and oxalate uptake when expressed in Xenopus laevis oocytes, Slc26a1 transports only SO 4 2 − and oxalate. Measurement of intracellular pH during the removal of extracellular Cl− in the presence and absence of HCO 3 − indicates that Slc26a6 functions as both a Cl−/HCO 3 − and a Cl−/OH− exchanger; simultaneous membrane hyperpolarization during these experimental maneuvers reveals that HCO 3 − and OH− transport mediated by S...