ADAMTS13 is a member of the ADAMTS (a disintegrin and metalloproteinase with thrombospondin motif) protein family. Members of the family share several distinct protein modules, including a propeptide region, a metalloproteinase domain, a disintegrin-like domain, and a thrombospondin type 1 (TS) motif. Individual members of this family differ in the number of C-terminal TS motifs, and some have unique C-terminal domains. The enzyme is the von Willebrand Factor (vWF)-cleaving protease, which is responsible for cleaving at the site of Tyr842-Met843 of the vWF molecule. A deficiency of this enzyme is associated with thrombotic thrombocytopenic purpura.