The CATSPER2 gene provides instructions for producing a protein that is found in the tail (flagellum) of sperm cells. The CATSPER2 protein plays a role in sperm cell movement (motility). It is one of four proteins that together form a hole (pore) that allows for the movement of charged calcium atoms (Ca<html:sup>2+</html:sup>) across the sperm cell membrane. Ca<html:sup>2+</html:sup> is needed for a type of sperm motility called hyperactivation. Hyperactivation is characterized by vigorous movements of the sperm tail, allow the sperm to push through the membrane of the egg cell during fertilization.