In the human, the channel is activated by progesterone released by the oocyte. Progesterone binds to the protein ABHD2 which is present in the sperm plasma membrane, which causes ABHD2 to cleave an inhibitor of CatSper (2-arachidonoylglycerol) into arachidonic acid and glycerol.
In humans, progesterone released by the oocyte activates a channel. This activation is mediated by progesterone binding to ABHD2 on the sperm plasma membrane, which subsequently cleaves an inhibitor of CatSper (2-arachidonoylglycerol) into arachidonic acid and glycerol.