Mediates electroneutral sodium- and carbonate-dependent chloride-HCO3(-) exchange with a Na(+):HCO3(-) stoichiometry of 2:1. Plays a major role in pH regulation in neurons. May be involved in cell pH regulation by transporting HCO3(-) from blood to cell. Enhanced expression in severe acid stress could be important for cell survival by mediating the influx of HCO3(-) into the cells. Also mediates lithium-dependent HCO3(-) cotransport. May be regulated by osmolarity (By similarity). Expressed in the Purkinje cells and dendrites in the molecular layer of the cerebellum (at protein level). Strong expression observed in testis and moderate expression in kidney inner medulla, the submandibular gland, eye, cerebrum and cerebellum. Belongs to the anion exchanger (TC 2.A.31) family.