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). Forms a complex with ATP6V1B1 and SLC9A3R1/EBP50. Interacts in a pH dependent-manner with CA2/carbonic anhydrase 2 (By similarity). Interacts with CFTR through SLC9A3R1/EBP50. Interacts with USH1C. 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 (By similarity). Expressed in the spiral ligament throughout the cochlea and in photoreceptors of the outer plexiform layer of the retina (at protein level). Repressed in the brain by chronic continuous hypoxia (at protein level). The PDZ-binding motif mediates interaction with the CFTR, SLC9A3R1/EBP50 complex and probably with USH1C. Deafness and blindness due to degeneration of sensory receptors in internal ear and retina. Belongs to the anion exchanger (TC 2.A.31) family.