Carboxypeptidase B2

Carboxypeptidase B2 (CPB2), also known as carboxypeptidase U (CPU), plasma carboxypeptidase B (pCPB) or thrombin-activatable fibrinolysis inhibitor (TAFI), is an is_associated_with::enzyme that, in humans, is encoded by the is_associated_with::gene CPB2.

Function
CPB2 is synthesized by the liver and circulates in the plasma as a is_associated_with::plasminogen-bound is_associated_with::zymogen. When it is activated by proteolysis at residue Arg92 by the is_associated_with::thrombin/is_associated_with::thrombomodulin complex, CPB2 exhibits carboxypeptidase activity. Activated CPB2 reduces fibrinolysis by removing the is_associated_with::fibrin C-terminal residues that are important for the binding and activation of is_associated_with::plasminogen.

is_associated_with::Carboxypeptidases are enzymes that hydrolyze C-terminal peptide bonds. The carboxypeptidase family includes metallo-, serine, and cysteine carboxypeptidases. According to their substrate specificity, these enzymes are referred to as carboxypeptidase A (cleaving aliphatic residues) or carboxypeptidase B (cleaving basic amino residues). The protein encoded by this gene is activated by is_associated_with::thrombin and acts on carboxypeptidase B substrates. After thrombin activation, the mature protein downregulates is_associated_with::fibrinolysis.

Isozymes
Polymorphisms have been described for this gene and its promoter region. Available sequence data analyses indicate splice variants that encode different isoforms.