组织蛋白酶 G（Cathepsin G）是属于肽酶（蛋白酶）家族的酶蛋白。在人体内，该蛋白由CTSG基因编码。该基因编码的蛋白属于 S1 肽酶蛋白家族，存在于中性多形核白细胞的嗜天青颗粒中。该蛋白酶底物特异性与糜蛋白酶 C 相近，但进化亲缘关系更接近其他免疫丝氨酸蛋白酶，例如中性粒细胞弹性蛋白酶、颗粒酶。
组织蛋白酶 G 可参与吞噬病原体的杀灭与降解，同时参与炎症部位的结缔组织重塑。该蛋白对 DNA 具有高亲和力（该特性在丝氨酸蛋白酶中较为罕见），因此也可定位于中性粒细胞胞外诱捕网（NETs）。该基因存在利用可变多聚腺苷酸化信号产生的多种转录本变体。
功能：肝素结合；肽酶活性；丝氨酸型内肽酶活性。
Cathepsin G is an enzymatic protein belonging to the peptidase or protease families. In humans, it is coded by the CTSG gene. The protein encoded by this gene, a member of the peptidase S1 protein family, is found in azurophil granules of neutrophilic polymorphonuclear leukocytes. The encoded protease has a specificity similar to that of chymotrypsin C, but it is most closely related to other immune serine proteases, such as neutrophil elastase and the granzymes. Cathepsin G may participate in the killing and digestion of engulfed pathogens, and in connective tissue remodeling at sites of inflammation. It also localizes to Neutrophil extracellular traps (NETs), via its high affinity for DNA, an unusual property for serine proteases. Transcript variants utilizing alternative polyadenylation signals exist for this gene.
Serine protease with trypsin- and chymotrypsin-like specificity.
Also displays antibacterial activity against Gram-negative and Gram-positive bacteria independent of its protease activity. Prefers Phe and Tyr residues in the P1 position of substrates but also cleaves efficiently after Trp and Leu. Shows a preference for negatively charged amino acids in the P2' position and for aliphatic amino acids both upstream and downstream of the cleavage site. Required for recruitment and activation of platelets which is mediated by the F2RL3/PAR4 platelet receptor. Binds reversibly to and stimulates B cells and CD4+ and CD8+ T cells. Also binds reversibly to natural killer (NK) cells and enhances NK cell cytotoxicity through its protease activity. Cleaves complement C3. Cleaves vimentin. Cleaves thrombin receptor F2R/PAR1 and acts as either an agonist or an inhibitor, depending on the F2R cleavage site. Cleavage of F2R at '41-Arg-|-Ser-42' results in receptor activation while cleavage at '55-Phe-|-Trp-56' results in inhibition of receptor activation. Cleaves the synovial mucin-type protein PRG4/lubricin. Cleaves and activates IL36G which promotes expression of chemokines CXCL1 and CXLC8 in keratinocytes. Cleaves IL33 into mature forms which have greater activity than the unprocessed form. Cleaves coagulation factor F8 to produce a partially activated form. Also cleaves and activates coagulation factor F10. Cleaves leukocyte cell surface protein SPN/CD43 to release its extracellular domain and trigger its intramembrane proteolysis by gamma-secretase, releasing the CD43 cytoplasmic tail chain (CD43-ct) which translocates to the nucleus. Cleaves CCL5/RANTES to produce RANTES(4-68) lacking the N-terminal three amino acids which exhibits reduced chemotactic and antiviral activities. During apoptosis, cleaves SMARCA2/BRM to produce a 160 kDa cleavage product which localizes to the cytosol. Cleaves myelin basic protein MBP in B cell lysosomes at '224-Phe-|-Lys-225' and '248-Phe-|-Ser-249', degrading the major immunogenic MBP epitope and preventing the activation of MBP-specific autoreactive T cells. Cleaves annexin ANXA1 and antimicrobial peptide CAMP to produce peptides which act on neutrophil N-formyl peptide receptors to enhance the release of CXCL2. Acts as a ligand for the N-formyl peptide receptor FPR1, enhancing phagocyte chemotaxis. Has antibacterial activity against the Gram-negative bacteria N.gonorrhoeae and P.aeruginosa. Likely to act against N.gonorrhoeae by interacting with N.gonorrhoeae penA/PBP2. Exhibits potent antimicrobial activity against the Gram-positive bacterium L.monocytogenes. Has antibacterial activity against the Gram-positive bacterium S.aureus and degrades S.aureus biofilms, allowing polymorphonuclear leukocytes to penetrate the biofilm and phagocytose bacteria. Has antibacterial activity against M.tuberculosis. Mediates CASP4 activation induced by the Td92 surface protein of the periodontal pathogen T.denticola, causing production and secretion of IL1A and leading to pyroptosis of gingival fibroblasts. Induces platelet aggregation which is strongly potentiated in the presence of ELANE. Catalytic activity: Specificity similar to chymotrypsin C. Activity regulation: Inhibited by soybean trypsin inhibitor, benzamidine, the synthetic peptide R13K, Z-Gly-Leu-Phe-CH2Cl, phenylmethylsulfonyl fluoride, 3,4-dichloroisocoumarin, DFP, SBTI and alpha-1-antitrypsin. Inhibited by LPS from P.aeruginosa but not by LPS from S.minnesota. Not inhibited by elastinal, CMK, TLCK, ETDA or leupeptin. (Microbial infection) Inhibited reversibly by S.aureus EapH1. (Microbial infection) Activity is induced by the Td92 surface protein of the periodontal pathogen T.denticola.
Post-translational: Two C-terminal truncation variants have been identified, one which ends at Arg-243 and one which ends at Ser-244.
After centrifugation, we suggest addition of de-ionized water to the original volume (See COA), followed by gentle mixingto ensure adequate homogenization. If further dilution is required, please use the lyophilization buffer.
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