This gene encodes a member of the potassium-dependent sodium/calcium exchanger protein family. The encoded protein plays an important role in sodium/calcium exchange in retinal rod and cone photoreceptors by mediating the extrusion of one calcium ion and one potassium ion in exchange for four sodium ions. Mutations in this gene may play a role in congenital stationary night blindness. Alternatively spliced transcript variants encoding multiple isoforms have been observed for this gene. [provided by RefSeq, Dec 2011].