Metalloprotease involved in sperm function, possibly by modulating the processes of fertilization and early embryonic development. Degrades a broad variety of small peptides with a preference for peptides shorter than 3 kDa containing neutral bulky aliphatic or aromatic amino acid residues. Shares the same substrate specificity with MME and cleaves peptides at the same amide bond (By similarity). Preferential cleavage of polypeptides between hydrophobic residues, particularly with Phe or Tyr at P1'. Binds 1 zinc ion per subunit. Inhibited by thiorphan and phosphoramidon. A secreted form produced by proteolytic cleavage also exists. Predominantly expressed in testis. Weakly expressed in brain, kidney and heart. N-glycosylated. Belongs to the peptidase M13 family. Truncated N-terminus. Truncated N-terminus.