Izumo sperm-egg fusion protein (IPR029389)

Short name: IZUMO

Overlapping homologous superfamilies


Family relationships


Izumo is a protein with a single immunoglobulin (Ig) domain. Its expression has been found to be testis-specific [PMID: 1, PMID: 2]. Izumo is not detectable on the surface of fresh sperm, but becomes exposed after an exocytotic process, the acrosome reaction, has occurred. It is thought to bind to putative Izumo receptors on the oocyte. Studies have shown that knock-out mice (Izumo-/- males) were sterile despite normal mating behaviour and ejaculation, indicating the importance of the protein in fertilisation [PMID: 16574441]. Izumo is a typical type I membrane glycoprotein with one immunoglobulin-like domain and a putative N-glycoside link motif (Asn 204) [PMID: 15759005]. It contains cysteine residues thought to form a disulphide bridge, and a conserved GCL sequence motif.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.