Epididymal-specific lipocalin-5, major form; Associates with spermatozoa in the epididymal fluid but does not bind tightly to them. Binds both all-trans and 13-cis retinoic acid. May act as a retinoid carrier protein which is required for epididymal function and/or sperm maturation. Belongs to the calycin superfamily. Lipocalin family.

Izumo sperm-egg fusion protein 1; 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'.

Cysteine-rich secretory protein 3; This protein is supposed to help spermatozoa undergo functional maturation while they move from the testis to the ductus deferens; Belongs to the CRISP family.

Serine protease inhibitor Kazal-type 8; Probable serine protease inhibitor.

Disintegrin and metalloproteinase domain-containing protein 2; Sperm surface membrane protein that may be involved in sperm- egg plasma membrane adhesion and fusion during fertilization. Could have a direct role in sperm-zona binding or migration of sperm from the uterus into the oviduct. Interactions with egg membrane could be mediated via binding between its disintegrin-like domain to one or more integrins receptors on the egg. This is a non catalytic metalloprotease-like protein (By similarity).

Hyaluronidase PH-20; Involved in sperm-egg adhesion. Upon fertilization sperm must first penetrate a layer of cumulus cells that surrounds the egg before reaching the zona pellucida. The cumulus cells are embedded in a matrix containing hyaluronic acid which is formed prior to ovulation. This protein aids in penetrating the layer of cumulus cells by digesting hyaluronic acid.

Zonadhesin; Binds in a species-specific manner to the zona pellucida of the egg. May be involved in gamete recognition and/or signaling.

Disintegrin and metalloproteinase domain-containing protein 7; May play an important role in male reproduction including sperm maturation and gonadotrope function. This is a non catalytic metalloprotease-like protein.

Cadherin-1; Cadherins are calcium-dependent cell adhesion proteins. They preferentially interact with themselves in a homophilic manner in connecting cells; cadherins may thus contribute to the sorting of heterogeneous cell types. CDH1 is involved in mechanisms regulating cell-cell adhesions, mobility and proliferation of epithelial cells. Has a potent invasive suppressor role. It is a ligand for integrin alpha-E/beta-7 (By similarity). (Microbial infection) Does not function as a receptor for L.monocytogenes internalin A (InlA); mutating a single surface-exposed residue confers recep [...]