Acts as a sodium-independent DIDS-sensitive anion exchanger mediating bicarbonate, chloride, sulfate and oxalate transport. May play a role in the maintenance of the electrolyte and acid-base homeostasis in the kidney, by acting as a distal excretory segment-specific anion exchanger. Plays a major role in gastric acid secretion. Expressed in the cytoplasm in recycling endosomes of medullary collecting duct cells and in acid-secreting gastric parietal cells. Targeted to the basolateral membrane in hypertonicity and potassium depletion. Expressed in tonsillar high endothelial venule endothelial cells (HEVEC), placenta and in testis, expressed in a subgroup of basal cells in the epididymal ducts. Is active at both alkaline and acidic pH. Activity is inhibited by 4,4'-Di-isothiocyanatostilbene-2,2'-disulfonic acid (DIDS - an inhibitor of several anion channels and transporters). Belongs to the SLC26A/SulP transporter (TC 2.A.53) family.