The procollagen C-proteinase is a member of the subfamily Astacin of the family M12 (Astacin) of clan MB of metalloproteinases that specifically cleaves an Ala-Asp bond in type I/II procollagens, a Gly-Asp bond in type III procollage, and similar bonds in a precursor of lysyloxidase as well as in laminin 5. Three procollagen C-proteinase proteins encoded by different open reading frames (ORFs) of the same gene have been identified, including a 70 kDa polypeptide referred to as bone morphogenetic protein/C-proteinase (BMP-1/C-proteinase) or pCP1, an 80 kDa polypeptide referred to as bone morphogenetic protein/His (BMP-1/His) and a 100 kDa polypeptide referred to as mammalian tolloid (mTld) or pCP-2.