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 .
Subcellular locations: Cell membrane, Cytoplasmic vesicle, Secretory vesicle, Acrosome membrane
Localizes initially to the acrosome membrane of the sperm head (both outer and inner acrosomal membranes) . During the acrosome reaction, translocates to the plasma membrane (, ).
Sperm-specific (at protein level) (, ). Detectable on sperm surface only after the acrosome reaction (, ).