C11orf94/Frey is a key regulator for male fertility by controlling sperm fusion complex assembly

The sperm fusion complex built around the Izumo1 protein is the key male factor for mediation of gamete fusion. Loss of several complex members leads to male infertility. Here, we provide a detailed characterisation of the C11orf94/Frey protein which acts as central chaperone for assembly of the sperm fusion complex. By retaining Izumo1 in the endoplasmic reticulum, C11orf94 is essentially required to facilitate the recruitment of Izumo1-interacting proteins into the sperm fusion complex.