Izumo sperm-egg fusion 1 is a protein that in humans is encoded by the IZUMO1 gene.[5] In mammalian fertilisation, IZUMO1 binds to its egg receptor counterpart, Juno, to facilitate recognition and fusion of the gametes. [6]
Studies have shown that male Izumo knockout mice are sterile because their sperm are unable to fuse to the oocyte membrane.[1] Izumo -/- mice produced morphologically normal sperm that were able to penetrate the zona pellucida, but could not fuse with to the eggs. In-vitro human experiments have also been conducted, suggesting that Izumo is required for human gamete fusion. [1]
Through the use of Western Blot analyses, it has been shown that Izumo is only expressed in the testis and is found on mature spermatozoa. [8] Izumo-1 located on mature spermatozoa that have undergone capacitation binds to its receptor Juno, which is located on the oolemma of eggs. [9]
^ Bianchi, Enrica, et al. "Juno is the egg Izumo receptor and is essential for mammalian fertilization." Nature 508.7497 (2014): 483.
^Inoue N, Ikawa M, Isotani A, Okabe M (2005). "The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs". Nature. 434 (7030): 234–8. doi:10.1038/nature03362. PMID15759005.
^ Ellerman DA, Pei J, Gupta S, Snell WJ, Myles D, Primakoff P. Izumo is part of a multiprotein family whose members form large complexes on mammalian sperm. Molecular reproduction and development. 2009;76(12):1188-1199.
^ Bianchi E, Doe B, Goulding D, Sanger Mouse Genetics Project, Wright GJ. Juno is the egg Izumo receptor and is essential for mammalian fertilisation. Nature. 2014;508(7497):483-487.
Yatsenko AN, Roy A, Chen R, Ma L, Murthy LJ, Yan W, Lamb DJ, Matzuk MM (2006). "Non-invasive genetic diagnosis of male infertility using spermatozoal RNA: KLHL10 mutations in oligozoospermic patients impair homodimerization". Hum. Mol. Genet. 15 (23): 3411–9. doi:10.1093/hmg/ddl417. PMID17047026.
Granados-Gonzalez V, Aknin-Seifer I, Touraine RL, Chouteau J, Wolf JP, Levy R (2008). "Preliminary study on the role of the human IZUMO gene in oocyte-spermatozoa fusion failure". Fertil. Steril. 90 (4): 1246–8. doi:10.1016/j.fertnstert.2007.09.008. PMID18082733.
Inoue N, Ikawa M, Okabe M (2008). "Putative sperm fusion protein IZUMO and the role of N-glycosylation". Biochem. Biophys. Res. Commun. 377 (3): 910–4. doi:10.1016/j.bbrc.2008.10.073. PMID18952059.
