function:Voltage-gated calcium channel that plays a central role in sperm cell hyperactivation. Controls calcium entry to mediate the hyperactivated motility, a step needed for sperm motility which is essential late in the preparation of sperm for fertilization. Activated by intracellular alkalinization.,similarity:Belongs to the cation channel sperm-associated family.,subunit:Heterotetramer; possibly composed of CATSPER1, CATSPER2, CATSPER3 and CATSPER4 (Potential). Interacts with CATSPER1.,tissue specificity:Testis-specific. Specifically present in the principal piece of sperm tail.,