Carboxypeptidase B2

"TAFI" redirects here. For other uses, see TAFI (disambiguation).

Carboxypeptidase B2 (CPB2), also known as carboxypeptidase U (CPU), plasma carboxypeptidase B (pCPB) or thrombin-activatable fibrinolysis inhibitor (TAFI), is an enzyme that, in humans, is encoded by the gene CPB2.^[5][6]

CPB2
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 3D66, 3D67, 3D68, 3LMS, 4P10, 5HVG, 5HVH, 5HVF
Identifiers
Aliases	CPB2, CPU, PCPB, TAFI, carboxypeptidase B2
External IDs	OMIM: 603101; MGI: 1891837; HomoloGene: 55610; GeneCards: CPB2; OMA:CPB2 - orthologs
Gene location (Human) Chr. Chromosome 13 (human)[1] Band 13q14.13 Start 46,053,186 bp[1] End 46,105,033 bp[1]
Gene location (Mouse) Chr. Chromosome 14 (mouse)[2] Band 14|14 D3 Start 75,479,727 bp[2] End 75,520,995 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right lobe of liver lower lobe of lung corpus epididymis tail of epididymis right lung testicle gallbladder upper lobe of lung upper lobe of left lung visceral pleura Top expressed in left lobe of liver primary oocyte zygote secondary oocyte human fetus fetal liver hematopoietic progenitor cell urethra sexually immature organism morula embryo More reference expression data BioGPS More reference expression data
Gene ontology Molecular function metal ion binding peptidase activity hydrolase activity zinc ion binding carboxypeptidase activity metallopeptidase activity metallocarboxypeptidase activity Cellular component extracellular exosome extracellular space extracellular region Biological process blood coagulation negative regulation of hepatocyte proliferation positive regulation of extracellular matrix constituent secretion liver regeneration cellular response to glucose stimulus negative regulation of plasminogen activation negative regulation of fibrinolysis response to heat hemostasis proteolysis fibrinolysis regulation of complement activation Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 1361 56373 Ensembl ENSG00000080618 ENSMUSG00000021999 UniProt Q96IY4 Q9JHH6 RefSeq (mRNA) NM_016413 NM_001278541 NM_001872 NM_019775 RefSeq (protein) NP_001265470 NP_001863 NP_062749 Location (UCSC) Chr 13: 46.05 – 46.11 Mb Chr 14: 75.48 – 75.52 Mb PubMed search [3] [4]
Wikidata
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Function

CPB2 is synthesized by the liver^[7] and circulates in the plasma as a plasminogen-bound zymogen. When it is activated by proteolysis at residue Arg92 by the thrombin/thrombomodulin complex, CPB2 exhibits carboxypeptidase activity. Activated CPB2 reduces fibrinolysis by removing the fibrin C-terminal residues that are important for the binding and activation of plasminogen.^[8][9]

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 thrombin and acts on carboxypeptidase B substrates. After thrombin activation, the mature protein downregulates fibrinolysis.^[10]

Fibrinolysis (simplified). Blue arrows denote stimulation, and red arrows inhibition.

Isozymes

Polymorphisms have been described for this gene and its promoter region. Available sequence data analyses indicate splice variants that encode different isoforms.^[10]

See also

• Carboxypeptidase B