Plays a role in the binding between sperm and oocytes (PubMed:20219979). Component of epididymosomes, one type of membranous microvesicules which mediate the transfer of lipids and proteins to spermatozoa plasma membrane during epididymal maturation. Also component of the CD9-positive microvesicules found in the cauda region. Located in the connecting piece of elongated spermatids and sperm (PubMed:20219979). Also located in the apical region of the sperm head after sperm capacitation (PubMed:20219979). Weakly attached to the cell membrane and later secreted into the extracellular space (PubMed:20219979). Located on sperm equatorial segment and neck (By similarity). Associated with epididymosomes from the caput and cauda epididymis (By similarity). Expressed in testis (at protein level). Little or no expression in other tissues tested. Detected at postnatal day 14 in developing testis (at protein level). Detected from postnatal day 18 onwards, with increasing levels through to postnatal day 36. N-glycosylated (PubMed:20219979). N-glycosylation decreases during the transit in the caput. Belongs to the CRISP family.