SPESP1

The encoded protein is a human alloantigen involved in sperm-egg binding and fusion.

Sperm Equatorial Segment Protein 1

Involved in fertilization ability of sperm.

Biological Process acrosome reactionManual Assertion Based On ExperimentIBA:GO_Central
Biological Process fertilizationISS:UniProtKB
Biological Process fusion of sperm to egg plasma membrane involved in single fertilizationManual Assertion Based On ExperimentIBA:GO_Central
Biological Process sperm-egg recognitionISS:UniProtKB

Cytoplasmic vesicle, secretory vesicle, acrosome
Small proacrosomal granules (during the Golgi phase), enlarged acrosomal vesicles (during the cap phase), acrosome (during the elongating phase), equatorial segment of the acrosome (during the maturation phase) (PubMed:12773409).
After acrosome reaction localizes to the equatorial segment region in both noncapacitated and capacitated, acrosome-reacted sperm (By similarity).

Glycosylated. In testis there are two predominant forms of 77- and 67-kDa and a form of 47-kDa, whereas in epididymal sperm from caput, corpus, and cauda there are two forms of 47- and 43-kDa. Testis forms contain complex carbohydrate residues. Epididymal sperm forms are N-glycosylated. Then undergoes significant glycosylation in the testis and that the majority of these glycoconjugates are removed by the time sperm reach the caput epididymis.