Sodium/potassium/calcium exchanger 1 (NCKX1), also known as SLC24A1, is an integral membrane protein that transports one calcium and one potassium ion in exchange for four sodium ions. It is expressed only in retinal rod photoreceptors. NCKX1 controls the calcium concentration of outer segments during light and darkness, and is a critical component of the visual transduction cascade [, , ]. Light causes a rapid lowering of cytosolic free calcium caused by extrusion via this protein, which plays a key role in light adaptation.
