Tissue specificityHighly expressed in testis, where it is localized in the acrosome of postmeiotic stages of spermiogenesis (round and elongating spermatids and in ejaculated spermatozoa) (at protein level). Poorly expressed in placenta and fetal lung.
Sequence similaritiesBelongs to the SPESP1 family.
Cellular localizationCytoplasmic 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.