IZUMO1

Essential sperm cell-surface protein required for fertilization by acting as a ligand for IZUMO1R/JUNO receptor on egg. The IZUMO1:IZUMO1R/JUNO interaction is a necessary adhesion event between sperm and egg that is required for fertilization but is not sufficient for cell fusion. The ligand-receptor interaction probably does not act as a membrane 'fusogen'. Acts a ligand for the human-specific oolemma epitope FCRL3/MAIA during fertilization. FCRL3/MAIA replaces IZUMO1R/JUNO as IZUMO1 receptor after sperm-egg adhesion, which permits species-specific gamete fusion. Plays a critical role in sperm-oolemma binding prior to plasma membrane fusion. Can mediate cell-cell fusion in cultured mammalian cells independently of its binding to IZUMO1R/JUNO (By similarity)..

Function from UniProtKB (Q8IYV9), read 2026-09-23. CC BY 4.0.