Thrombin Activatable Fibrinolytic Inhibitor and Venous Thrombosis

Synonyms

Carboxypeptidase B2, Plasma; CPB2CARBOXYPEPTIDASE U; CPU; TAFI

Definition and Characteristics

First purified as a 60-kd plasminogen binding protein from human plasma [1]. Predicted 423-amino acid protein was similar to tissue type carboxypeptidases A and B; Eaton et al designated the gene plasma carboxypeptidase B (pCPB) (different from carboxypeptidase N, now known as CPN [2]. Also known as carboxypeptidase U (CPU), it was observed that the zymogen pro-CPU had affinity for plasminogen and could be converted to the active form by thrombin-thrombomodulin complex and plasmin. By convention, CPU and pCPB are now recognized as TAFI. TAFI is mainly produced by the liver as a single chain protein of 401 amino acids and is a potent inhibitor of fibrinolysis by removing the fibrin C-terminal lysine and arginine residues that bind plasminogen. In the LETS study an increased concentration of TAFI was associated with