-ATPase (sodium-potassium adenosine triphosphatase, also known as the pump or sodium-potassium pump) is an enzyme  (an electrogenic transmembrane ATPase) found in the plasma membrane of all animal cells. The -ATPase enzyme is a solute pump that pumps sodium out of cells while pumping potassium into cells, both against their concentration gradients. This pumping is active (it uses energy from ATP) and is important for cell physiology. An example application is nerve conduction.