CatSperZ is a subunit of 9-subunit CatSper ion channel complex, involved in sperm cell hyperactivation [, , ]. Disruption of CatSperZ resulted in male subfertility; fewer calcium ions were able to pass through the channels to enter the cell, affecting the proximal flagellum flexibility and preventing sperm from migrating efficiently. CatSperZ may represent an evolutionary adaptation to maximize fertilization inside the mammalian female reproductive tract []. Together with EFCAB9, CatSperZ associates with the CatSper channel pore and is required for the two-row structure of each single CatSper channel [].
