ADAM32 was first discovered in a search for testis-specific proteinases. ADAM32 was identified in human, rat, mouse, macaque and chimp, and thus far has been found only in testis. In mice, ADAM32 is found on the sperm surface, where it may play a role in fertilization. ADAM32 is a member of the ADAMs family (A Disintegrin And Metalloproteinase), but does not contain the canonical HExxHxxxxH zinc-binding metalloproteinase catalytic site. The domain structure of the full length ADAM32 includes a signal sequence, propeptide domain, metalloproteinase-like domain, disintegrin-like domain, cys-rich domain, EGF-like domain, a short spacer region, then the transmembrane domain and a cytoplasmic domain. Like many of the reproductive-specific ADAMS, ADAM32 plays a non-enzymatic role, or (as is the case for ADAMs 1 & 2 (fertilin alpha and beta)), the protein acts in concert with a proteolytically active ADAM to process proteins. Little is known about interactions between ADAM32 and other ADAMs. Several different sequences for human ADAM32 are published; 787, 688, 649, 629, and 279 amino acids in length. The 688 amino acid form is identical to the 787 AA form until the EGF-like domain, and lacks the TM and cytoplasmic domains. The 649 AA form is likewise identical to the longer form, just to the start of the TM domain, and also lacks the TM and cytoplasmic domains. The 629 AA form has a deletion of 107 residues midway into the MP-like domain, and lacks the amino end of the disintegrin domain, but contains the rest of the domains found in the full-length ADAM32. The predicted masses for the different versions are 87.8, 76.9, 72.9, 70.9 and 32.1, respectively, for the 786, 688, 649, 629 and 279 AA forms.