Interacts with IZUMO1. Disappears from acrosome reacted sperm. Co-localizes with IZUMO1 at acrosomal cap area. Expressed in sperm and testis (at protein level) (PubMed:20421979). Expressed in heart and testis (PubMed:17597519). Not detected in kidney, lung, liver, brain, ovary, spleen and thymus (PubMed:17597519, PubMed:20421979). No visible phenotype. Sperm have normal fertilizing ability. Belongs to the peptidase M2 family. Lacks the conserved Glu residue in position 378 necessary for the catalytic activity.