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 (By similarity). 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 (By similarity). Expressed in gastric epithelium, predominantly in the gastric parietal cells but also at lower levels in mucosal cells. Belongs to the SLC26A/SulP transporter (TC 2.A.53) family.