granzyme b

Granzyme B(GZMB) contains 1 peptidase S1 domain and belongs to the peptidase S1 family. This enzyme is necessary for target cell lysis in cell-mediated immune responses. It cleaves after Asp and seems to be linked to an activation cascade of caspases (aspartate-specific cysteine proteases) responsible for apoptosis execution. The protein cleaves caspase-3, -7, -9 and 10 to give rise to active enzymes mediating apoptosis.

Granzyme B Protein, Human, Recombinant (E. coli, His) is expressed in E. coli expression system with N-6xHis tag. The predicted molecular weight is 31.0 kDa and the accession number is P10144.

Granzyme B, also known as GZMB, is the most prominent member of the granzyme family of cell death-inducing serine proteases expressed in the granules of cytotoxic T lymphocytes (CTLs) and NK cells. Granzyme B enters the target cells depending on another membrane-binding granule protein, perforin, results in the activation of effector caspases and mitochondrial depolarization through caspase-dependent and -independent pathways, and consequently induces rapid cell apoptosis. Over 3 substrates of GZMB have been identified including the key substrate caspase-3, ICAD, and Bid. GZMB is suggested to protect the host by lysing cells bearing on their surface 'nonself' antigens such as bacterial and viral infected-cells and tumor cells and accordingly plays an essential role in immunosurveillance.

Granzymes are key components of the immune response that play important roles in eliminating host cells infected by intracellular pathogens. Several granzymes are potent inducers of cell death. A total of eight granzymes (A-G and M) have been identified in the mouse, but only five are known in humans (A, B, H, M, and granzyme 3), and granzyme H appears to be specifically human. Human granzyme H is a neutral serine protease that is expressed predominantly in the lymphokine-activated killer (LAK)/natural?killer (NK) compartment of the immune system. In adenovirus-infected cells in which granzyme B (gzmB) and downstream apoptosis pathways are inhibited, granzyme H directly cleaves the adenovirus DNA-binding protein (DBP), a viral component required for viral DNA replication. This virus demonstrated that gzmH directly induces an important decay in viral DNA replication. Interestingly, gzmH also cleaves the adenovirus 1K assembly protein, a major inhibitor of gzmB, and relieves gzmB inhibition. Granzyme H has a very high amino acid identity (>9%) with many portions of the granzyme B sequence, particularly near the amino terminus of the molecule despite performing a distinct enzymic function.

Bid, BH3-interacting domain death agonist, was initially cloned based in its ability to interact with both Bcl-2 and Bax. Bid contains only the BH3 domain, which is required for its interaction with the Bcl-2 family proteins and for its pro-death activity. Bid is susceptible to proteolytic cleavage by caspases, calpains, Granzyme B and cathepsins. Bid is important to cell death mediated by these proteases and thus is the sentinel to protease-mediated death signals.

SerpinB9, also known as Cytoplasmic antiproteinase 3, CAP-3, Peptidase inhibitor 9, SERPINB9 and PI-9, is a cytoplasm protein that belongs to the serpin family and Ov-serpin subfamily. Serpin-B9 ( CAP-3 / PI-9 ) is the only known human intracellular inhibitor of granzyme B (GrB), the effector molecule in immunity against cytomegalovirus (CMV) and in renal allograft rejection. Serpin-B9 and SPI-6 expression in immune-privileged cells, APCs, and CTLs protect these cells against the actions of granzyme B, and when expressed in tumor cells or virally infected hepatocytes, confers resistance to killing by CTL and NK cells. Expression of increasing levels of Serpin-B9 ( CAP-3 / PI-9 ) in target cells may progressively inhibit immune surveillance by blocking NK and CTL-induced cytotoxicity through the perforin / granzyme pathway and then through the Fas / FasL pathway. Serpin-B9 ( CAP-3 / PI-9 ) is selectively up-regulated in hepatocytes in response to infiltration of the liver by NK cells that express perforin and enzymatically active granzyme B. Upregulated expression of Serpin-B9 ( CAP-3 / PI-9 ) in NSCLC cells may serve to protect them from apoptosis induced by GrB.

Serine protease inhibitor A3N(Serpin A3N) is a serine protease inhibitor that is structurally related to α1 antichymotrypsin encoded by the SERPINA3 gene. Serpin A3N is highly expressed in brain, testis, lung, thymus, and spleen. It is expressed with low levels in bone marrow, kidney and skeletal muscle. Serpin A3N secreted by Sertoli cells may regulate the activity of locally produced Granzyme B. Granzyme B inhibition by Serpin A3N may therefore regulate Granzyme Bmediated killing by cytotoxic lymphocytes, providing a means to disable cellmediated immune responses.

Caspase-10 (CASP10) is a 521 amino acid protein member of the Cysteine-Aspartic Acid Protease (Caspase) family. CASP10 contains two DED (Death Effector) domains and is detectable in most tissues. CASP10 cleavage by Granzyme B and autocatalytic activity generate the two active subunits: Caspase-10 subunit p23/17, Caspase-10 subunit p12. Caspases are a family of cytosolic aspartate-specific cysteine proteases involved in the execution-phase of cell apoptosis, the initiation and execution. Human caspases can be subdivided into three functional groups: cytokine activation (caspase-1, -4, -5, and -13), apoptosis initiation (caspase-2, -8, -9, -and -10), and apoptosis execution (caspase-3, -6, and -7). CASP10 cleaves and activates caspases 3 and 7, but itself is processed by caspase 8. Defects in CASP10 are associated with apoptosis defects seen in type II autoimmune lymphoproliferative syndrome.