Electroneutral sodium- and bicarbonate-dependent cotransporter with a Na(+):HCO3(-) 1:1 stoichiometry. Regulates intracellular pH and may play a role in bicarbonate salvage in secretory epithelia. May also have an associated sodium channel activity. Transporter activity is regulated by CA2/carbonic anhydrase 2, cAMP and PKA. Insensitive to stilbene derivatives. May be inhibited by 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) (By similarity). Interacts with USH1C. Forms a complex with ATP6V1B1 and SLC9A3R1/EBP50. Interacts in a pH dependent-manner with CA2/carbonic anhydrase 2 (By similarity). Interacts with CFTR probably through SLC9A3R1/EBP50. Also described at the apical cell membrane. Localizes to the stereocilia of cochlear outer hair cells and to the lateral membrane of cochlear inner hair cells. Expressed in aorta, ventricles, atrium, mesenteric artery, kidney, spleen, duodenum, jejunum, ileum, colon, lung, trachea, gastric fundus and pylorus, cerebrum, cerebellum, pancreas, liver, parotid gland, and epididymis. Expressed in the inner ear by cochlear outer and inner hair cells (at protein level). Highly expressed in testis and spleen. Also detected in heart, brain, lung, liver and kidney. Isoform 4 and isoform 5 are specifically expressed in kidney. Isoform 6 is specifically expressed in hippocampal neurons. Up-regulated in kidney upon metabolic acidosis. The PDZ-binding motif mediates interaction with the CFTR, SLC9A3R1/EBP50 complex and probably with USH1C. N-glycosylated. Belongs to the anion exchanger (TC 2.A.31) family.