sodium-calcium exchanger

The sodium-calcium exchanger (often denoted Na⁺/Ca²⁺ exchanger, NCX, or exchange protein) is an antiporter membrane protein that removes calcium from cells. It uses the energy that is stored in the electrochemical gradient of sodium (Na⁺) by allowing Na⁺ to flow down its gradient across the plasma membrane in exchange for the countertransport of calcium ions (Ca²⁺). The NCX removes a single calcium ion in exchange for the import of three sodium ions. The exchanger exists in many different cell types and animal species. The NCX is considered one of the most important cellular mechanisms for removing Ca²⁺.