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Matches in DBpedia 2016-04 for { ?s ?p "C3 convertase (EC 3.4.21.43, Classical-complement-pathway C3/C5 convertase, C overbar 42 , C4b,2a, C5 convertase, C overbar 423, C4b,2a,3b, C42, C5 convertase, C423, C4b,2a,3b, complement C.hivin.4.hivin2, complement C3 convertase) belongs to family of serine proteases and is necessary in innate immunity as a part of complement system which eventuate in opsonisation of particles, release of inflammatory peptides, C5 convertase formation and cell lysis. C3 convertase exists in two forms (C3bBb and C4bC2a) but both of them cleave only C3, central molecule of complement system.The complement system can be activated in three different pathways: the classical, lectin, and alternative pathways. All of these activation pathways lead to enzymatic cleavage of C3. Newly created fragments C3a and C3b are important in next steps of complement cascade development. The smaller fragment called C3a is released and stimulates inflammation through the chemoattractant activity. C3b, the larger fragment, becomes covalently attached to the microbial surface or to the antibody molecules through the thioester domain at the site of complement activation. After cleavage and binding to cell surface, the C3b fragment is ready to bind a plasma protein called Factor B. The Factor B (a zymogen) is cleaved by a plasma serine protease Factor D releasing a small fragment called Ba and generating a larger fragment called Bb that remains attached to C3b. Also Mg2+ ions are necessary for forming a functional C3 convertase. Thus, the alternative pathway C3 convertase is formed and is able to cleave C3 now.Another form, the classical pathway C3 convertase contains different proteins of complement system – C4b and C2a. These fragments form during the classical or lectin pathway of the complement. The cleavage of C4 and C2 is mediated by serine proteases - C1 complex (C1q, C1r, C1s) in classical pathway and Mannose-binding lectin-associated serine proteases (MASPs: MASP1, MASP2, MASP3) in lectin pathway. C4 is homologous to C3, and C4b contains an internal thioester bond, similar to that in C3b, that forms covalent amide or ester linkages with the antigen-antibody complex or with the adjacent surface of a cell to which is antibody bound. C2 is cleaved by C1s to a smaller fragment called C2b and larger fragment called C2a that binds to C4b. The fragments C4a and C2b are released.Once formed, both C3 convertases will catalyze the proteolytic cleavage of C3 into C3a and C3b (hence the name "C3-convertase"). C3b can then act as an opsonin or bind to activated bimolecular complex C4b2a to form a trimolecular complex, C5 convertase, which is a specific enzyme for C5."@en }

• Q5008114 abstract "C3 convertase (EC 3.4.21.43, Classical-complement-pathway C3/C5 convertase, C overbar 42 , C4b,2a, C5 convertase, C overbar 423, C4b,2a,3b, C42, C5 convertase, C423, C4b,2a,3b, complement C.hivin.4.hivin2, complement C3 convertase) belongs to family of serine proteases and is necessary in innate immunity as a part of complement system which eventuate in opsonisation of particles, release of inflammatory peptides, C5 convertase formation and cell lysis. C3 convertase exists in two forms (C3bBb and C4bC2a) but both of them cleave only C3, central molecule of complement system.The complement system can be activated in three different pathways: the classical, lectin, and alternative pathways. All of these activation pathways lead to enzymatic cleavage of C3. Newly created fragments C3a and C3b are important in next steps of complement cascade development. The smaller fragment called C3a is released and stimulates inflammation through the chemoattractant activity. C3b, the larger fragment, becomes covalently attached to the microbial surface or to the antibody molecules through the thioester domain at the site of complement activation. After cleavage and binding to cell surface, the C3b fragment is ready to bind a plasma protein called Factor B. The Factor B (a zymogen) is cleaved by a plasma serine protease Factor D releasing a small fragment called Ba and generating a larger fragment called Bb that remains attached to C3b. Also Mg2+ ions are necessary for forming a functional C3 convertase. Thus, the alternative pathway C3 convertase is formed and is able to cleave C3 now.Another form, the classical pathway C3 convertase contains different proteins of complement system – C4b and C2a. These fragments form during the classical or lectin pathway of the complement. The cleavage of C4 and C2 is mediated by serine proteases - C1 complex (C1q, C1r, C1s) in classical pathway and Mannose-binding lectin-associated serine proteases (MASPs: MASP1, MASP2, MASP3) in lectin pathway. C4 is homologous to C3, and C4b contains an internal thioester bond, similar to that in C3b, that forms covalent amide or ester linkages with the antigen-antibody complex or with the adjacent surface of a cell to which is antibody bound. C2 is cleaved by C1s to a smaller fragment called C2b and larger fragment called C2a that binds to C4b. The fragments C4a and C2b are released.Once formed, both C3 convertases will catalyze the proteolytic cleavage of C3 into C3a and C3b (hence the name "C3-convertase"). C3b can then act as an opsonin or bind to activated bimolecular complex C4b2a to form a trimolecular complex, C5 convertase, which is a specific enzyme for C5.".