This is the catalytic component of the active enzyme, which catalyzes the hydrolysis of ATP coupled with the exchange of sodium and potassium ions across the plasma membrane. This action creates the electrochemical gradient of sodium and potassium ions, providing the energy for active transport of various nutrients. Plays a role in sperm motility. ATP + H2O + K(+)(out) + Na(+)(in) = ADP + H(+) + K(+)(in) + Na(+)(out) + phosphate Specifically inhibited by an endogenous cardiac glycoside, ouabain. The sodium/potassium-transporting ATPase is composed of a catalytic alpha subunit, an auxiliary non-catalytic beta subunit and an additional regulatory subunit. In mature sperm, located in the principle piece of the sperm flagellum. Specifically expressed in testis. Found in very low levels in skeletal muscle. Expressed in mature sperm (at protein level). Belongs to the cation transport ATPase (P-type) (TC 3.A.3) family. Type IIC subfamily. Truncated N-terminus. Truncated N-terminus.