ADAM32 (a disintegrin and metalloprotease domain 32) is a 90-100kD member of the M12B peptidase family of proteins. It is expressed on sperm found in the testis, epididymis and vas deferens. The human ADAM32 proprecursor is a 771aa type I transmembrane protein. It contains a 158 aa proregion (aa17-174) and a 508aa extracellular domain (ECD) (aa175-682). The ECD contains a nonfunctional metalloprotease domain (aa186-383), an integrin-binding disintegrin region (aa391-479), a Cys-rich segment (aa480-502) and an EGF-like domain (aa 622-654). In the testis, mature ADAM32 is approximately 98kD in size; in the epididymis, cleavage occurs after the metalloprotease domain to generate a 44kD product. There are two potential splice events that show a deletion of aa306-401 plus a 53aa substitution for the N-terminal 46aa. Over aa17-476, human ADAM32 is 66% aa identical to mouse ADAM32.