Mammalian spermatozoa become motile at ejaculation, but before they can fertilize the egg, they must acquire more thrust to penetrate the cumulus and zona pellucida. The forceful asymmetric motion of hyperactivated spermatozoa requires Ca2+ entry into the sperm tail by an alkalinization-activated voltage-sensitive Ca2+-selective current (ICatSper). Hyperactivation requires CatSper1 and CatSper2...

Ca(2+)-dependent mechanisms are critical for successful completion of fertilization. Here, we demonstrate that CRISP1, a sperm protein involved in mammalian fertilization, is also present in the female gamete and capable of modulating key sperm Ca(2+) channels. Specifically, we show that CRISP1 is expressed by the cumulus cells that surround the egg and that fertilization of cumulus-oocyte comp...

Mammalian spermatozoa gain competence to fertilize an oocyte as they travel through the female reproductive tract. This process is accompanied by an elevation of sperm intracellular calcium and a membrane hyperpolarization. The latter is evoked by K(+) efflux; however, the molecular identity of the potassium channel of human spermatozoa (hKSper) is unknown. Here, we characterize hKSper, reporti...