Sodium/Potassium/Calcium Exchanger 2 (NCKX2)

The outer segment of retinal rod and cone photoreceptors contains electrogenic sodium-calcium exchangers which mediate a light-induced decrease in free calcium concentration. This function in cones is performed by SLC24A2. The deduced 661-amino acid protein contains 12 transmembrane segments. NCKX2 shares 76.5% and 89.6% amino acid identity with chicken and rat Nckx2, respectively.

Northern blot analysis detected an approximately 10.5-kb NCKX2 transcript in human retina and frontal, temporal, parietal, and occipital lobes and cerebellum, but not in lung. In situ hybridization of chicken retina detected Nckx2 within cones, in some cells of the retinal ganglion cell layer, and in cell bodies at the base of the outer nuclear layer.