Cation channel sperm-associated auxiliary subunit eta (CATSPERH)

Cation channel sperm-associated auxiliary subunit eta (CATSPERH) is a transmembrane auxiliary protein of the CatSper ion channel complex, exclusively expressed in sperm and essential for its assembly, dimerization, and trafficking into the sperm flagellum. CATSPERH acts as a scaffold to stabilize pore-forming subunits—particularly CATSPER4—within the CatSper complex, and enables formation of a channel dimer required for the specialized zig-zag nanodomain architecture of CatSper in flagellar membranes. Loss of CATSPERH disrupts CatSper channel assembly and localization, rendering sperm immotile and male mice infertile. Genetic studies confirm the importance of CATSPERH as a molecular “checkpoint” in sperm-specific calcium signaling crucial for hyperactivation and fertilization. There are currently no drugs targeting CATSPERH directly, and its role is restricted to sperm biology, with no established links to pathologies beyond male infertility in humans and rodents.

Other names

Cation channel sperm-associated auxiliary subunit TMEM262TMEM262CATSPERHCation channel sperm-associated auxiliary subunit etaTransmembrane protein 262Cation channel sperm-associated auxiliary subunit theta (CATSPERθ; see note above)TMEM249 (occasionally used, though TMEM262 is the preferred)

Not applicable; no drugs known to target CATSPERH directly. In principle, small molecules inhibiting CatSper channel function—by blocking assembly or trafficking—would affect sperm calcium influx and motility, potentially leading to contraceptive effects.