Phospholipid-transporting ATPase IK (Atp8b3)

P4-ATPase flippase that catalyzes the hydrolysis of ATP coupled to the transport of aminophospholipids from the outer to the inner leaflet of various membranes and ensures the maintenance of asymmetric distribution of phospholipids. Phospholipid translocation appears also to be implicated in vesicle formation and in uptake of lipid signaling molecules.

May be responsible for the maintenance of asymmetric distribution of phosphatidylserine (PS) in spermatozoa membranes. Involved in acrosome reactions and binding of spermatozoa to zona pellucida.