Izumo1r
Function
Receptor for IZUMO1 present at the cell surface of oocytes (oolemma), which is essential for species-specific gamete recognition and fertilization (PubMed:24739963, PubMed:26859261, PubMed:27309808, PubMed:27416963). 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 (PubMed:24739963, PubMed:26859261, PubMed:27309808). The ligand-receptor interaction probably does not act as a membrane 'fusogen' (PubMed:24739963, PubMed:26859261, PubMed:27309808). Does not bind folate (PubMed:24739963).
Post-translational modifications
The protein is rapidly cleaved following fertilization, being only weakly detectable in zona-intact fertilized eggs at telophase II and undetectable at the pronuclear stage (PubMed:24739963). Sheding is probably required to block to polyspermy and ensuring egg fusion with a single sperm (PubMed:24739963).
Sequence Similarities
Belongs to the folate receptor family.
Tissue Specificity
Widely expressed with higher expression in thymus, spleen and lung (PubMed:11111049). Present at the cell surface of unfertilized oocytes, while it is barely detectable 30 to 40 minutes after fertilization (at protein level) (PubMed:24739963).
Cellular localization
- Cell membrane
- Lipid-anchor
- GPI-anchor
- GPI-anchored at the oolemma.
Alternative names
Folbp3, Folr4, Juno, Izumo1r, Sperm-egg fusion protein Juno, Folate receptor 4, Folate receptor delta, Folate-binding protein 3, IZUMO1 receptor protein JUNO, FR-delta