ADAMTS13 and thrombotic thrombocytopenic purpura: This exosite interacts with the spacer domain of ADAMTS‐13, i.e. Arg568, Arg660, Tyr661, and Tyr665, which is the antigenic region recognized by autoantibodies generated and found in patients with acquired TTP 69, 70 (see also the GoF ADAMTS‐13 variant mentioned above).