Calcium, potassium:sodium antiporter that transports 1 Ca(2+) and 1 K(+) in exchange for 4 Na(+) . Critical component of the visual transduction cascade, controlling the calcium concentration of outer segments during light and darkness . Light causes a rapid lowering of cytosolic free calcium in the outer segment of both retinal rod and cone photoreceptors and the light-induced lowering of calcium is caused by extrusion via this protein which plays a key role in the process of light adaptation .
Subcellular locations: Cell membrane
Expressed in the retina, particularly in the inner segment, outer and inner nuclear layers, and ganglion cell layer.