Izumo sperm-egg fusion protein 1 (IZUMO1)-Folate receptor 4 (Juno) protein-protein interface (IZUMO1-JUNO)

The Izumo sperm-egg fusion protein 1 (IZUMO1)-Folate receptor 4 (Juno) protein-protein interface is the essential molecular recognition event that facilitates the fusion of sperm and egg membranes in mammals (Inoue et al., 2005; Bianchi et al., 2014). IZUMO1 is a transmembrane protein of the immunoglobulin superfamily expressed on the surface of mature sperm, while Juno is a GPI-anchored receptor located on the oocyte plasma membrane (Aydin et al., 2016). The physical binding of IZUMO1 to Juno initiates the fusion process; notably, Juno is rapidly shed from the egg surface following fertilization to prevent polyspermy (Bianchi et al., 2014). Because this interaction is highly specific and indispensable for natural conception, it is a major focal point for the development of non-hormonal contraceptives designed to block the interface (Ohto et al., 2016). Additionally, mutations or deficiencies in either protein are associated with cases of unexplained infertility, positioning the interface as a diagnostic biomarker for reproductive health (Jean et al., 2019). Research is currently directed toward identifying small molecules and biologics that can disrupt this protein-protein interaction with high affinity and specificity to provide reversible fertility control.

Other names

IZUMO1-FOLR4 interfaceIzumo sperm-egg fusion protein 1-folate receptor 4 complexSperm-egg fusion interfaceIZUMO1-JUNO complex

Competitive inhibition of the physical interaction between sperm-surface IZUMO1 and egg-surface JUNO to prevent gamete membrane fusion and fertilization.