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. Activity is inhibited by 4,4'-Di-isothiocyanatostilbene-2,2'-disulfonic acid (DIDS - an inhibitor of several anion channels and transporters). Expressed in the pyramidal cells of the hippocampus (at protein level). Highly expressed in all major regions of the brain, spinal column and in testis, and moderate levels in trachea, thyroid and medulla region of kidney. Low expression levels observed in pancreas and kidney cortex. May be due to an intron retention. May be due to an intron retention. Belongs to the anion exchanger (TC 2.A.31) family.