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Information on EC 3.4.21.43 - classical-complement-pathway C3/C5 convertase
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3.4.21.43 classical-complement-pathway C3/C5 convertaseSpecify your search results
Word Map
The expected taxonomic range for this enzyme is: Eukaryota, Bacteria
Reaction Schemes
Selective cleavage of Arg-/-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-/- bond in complement component C5 alpha-chain to form C5a and C5b
Synonyms
c3bbbp, c4b2a, classical pathway c3 convertase, classical c3 convertase, c4b,2a, classical pathway c5 convertase, complement c3 convertase, c4bc2a, cp c3 convertase, soluble c3 convertase, 
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SYNONYM 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
C3 convertase
C3/C5 convertase
C3bBb
C4
-
-
-
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C423
-
-
-
-
C4b,2a
-
-
-
-
C4b,2a,3b
-
-
-
-
C4b,C2a
C4b2a
C5 convertase
classical pathway C3 convertase
classical pathway C3/C5 convertase
complement C3 convertase
-
-
-
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EC 3.4.21.44
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-
formerly
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C3 convertase
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-
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C3 convertase
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C3/C5 convertase
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-
-
-
C5 convertase
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-
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REACTION
REACTION DIAGRAM
COMMENTARY
ORGANISM
UNIPROT
LITERATURE
Selective cleavage of Arg-/-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-/- bond in complement component C5 alpha-chain to form C5a and C5b
Selective cleavage of Arg-/-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-/- bond in complement component C5 alpha-chain to form C5a and C5b
hydrolyses peptide bond 77 (Arg-Ser) in complement component C3, and complement component C5. Cleavage of C5 requires complement fragment C3b which binds C5 and renders it susceptible to cleavage by the C4b,C2a complex
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Selective cleavage of Arg-/-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-/- bond in complement component C5 alpha-chain to form C5a and C5b
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REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
hydrolysis of peptide bond
-
-
-
-
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CAS REGISTRY NUMBER
COMMENTARY
56626-15-4
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SUBSTRATE
PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
complement component C3 + H2O
?
-
classical pathway of the complement system
-
-
?
complement component C3 + H2O
component C3b + anaphylatoxin C3a
-
-
iC3b is generated by Factor I after formation of C3b. iC3b is a proteolytically inactive form of C3b that retains the ability to opsonize microbes, but cannot participate in convertase function
-
?
complement component C5 + H2O
?
-
activity of enzyme bound to component C3b
-
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
-
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
-
-
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
hydrolyzes peptide bond Arg77-Ser of the alpha-chain of C3
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
complement component C3 is the preferred substrate. Cleavage of the preferred C3 substrate and deposition of C3b effectively switches the output of the enzyme from C3b to C5b, resulting in initiation of the cytosolic process of complement
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
C3 complement cleavage is a central event in the activation of the complement system via the classical, the alternative, and the lectin pathway, overview
-
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
-
-
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
hydrolyzes peptide bond Arg77 of the alpha-chain of complement component C5, cleavage of C5 requires complement fragment C3b which binds C5 and renders it susceptible to cleavage by the C4b,C2a complex
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
C5 convertases C4b2aC3b and C3b 2 Bb
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
C5 convertases, C4b2a3b and C3b2Bb, cleave C5 into the anaphylatoxin C5a and C5b followed by initiation of the terminal pathway, leading to formation of lytic C5b-9 membrane attack complexes, overview
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-
?
complement component C5 + H2O
complement component C5a + complement component C5b
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C5 convertases, C4b2a3b and C3b2Bb, cleave C5 into the anaphylatoxin C5a and C5b, overview
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-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
C5 convertases, C4b2a3b and C3b2Bb, cleave C5 into the anaphylatoxin C5a and C5b, overview
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-
?
complement componentC3 + H2O
complement component C3a + complement component C3b
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C3 convertase C3bBb
-
-
?
complement componentC3 + H2O
complement component C3a + complement component C3b
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C3 convertases, C4b2a and C3bBb, cleave C3 into the anaphylatoxin C3a and C3b, overview
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-
?
complement componentC3 + H2O
complement component C3a + complement component C3b
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C3 convertases, C4b2a and C3bBb, cleave C3 into the anaphylatoxin C3a and C3b, overview
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-
?
additional information
?
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dissociation of the classical-complement-pathway C3/C5 convertase by the regulators decay-accelerating factor, DAF, complement receptor 1, CR1, factor H and C4-binding protein C4BP, controls the function of the enzyme. Decay acceleration mediated by DAF, C4BP and CR1 requires interaction of the alpha4/5 region of C2a with a CCP2/CCP3 site of DAF or structurally homologous sites of CR1 and C4BP
-
?
additional information
?
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the enzyme has a very short half-life. Dissociation of the two noncovalently bound subunits proceeds with a half_life of 1-3 min at 37°C under physiological conditions, and this rate increases greatly if regulatory proteins are present. Numerous decay-accelerating proteins are present in plasma and on host cells that bind to the noncatalytic subunit C4b and increase the rate at which the catalytic subunit C2a is released into the medium. C2a loses its enzymatic activity and its ability to bind to C4b upon release. Although C4b is able to rebind C2 and reform the enzyme, the interaction with most decay-accelerating factors also leads to permanent proteolytic interaction of the cell-bound subunit C4b by a fluid-phase protease Factor I. Theses regulatory events limit cleavage of C3, reduce release of the anaphylatoxin C3a and control the formation of more efficient C5 convertase enzymes
-
?
additional information
?
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factor B associates with complement component C3b and after proteolysis yields the C3 convertase of the alternative pathway, complement component C2A provides the catalytic center to the convertase complexes of the classical and lectin-binding pathways of complement activation, structural basis of the substrate specificity of the complement complex, overview, attachment of C3b to either C4b2a or C3bBb yields the C5 convertases, C4b2a3b and C3b2Bb, respectively, that cleave complement component C5
-
-
?
additional information
?
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the alternative pathway lead via C3 convertase C3bBb and the C5 convertases C4b2aC3b and C3b 2 Bb
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-
?
additional information
?
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the C3 convertases, bimolecular complexes C4b2a and C3bBb, of the classical and alternative pathways are the central enzymes of the complement cascade, focused complement activation on foreign targets depends on regulatory proteins that decay the bimolecular C3 convertases, activity and regulation of complement control proteins CCP1-CCP4 as modules of the cell surface regulator, decay-accelerating factor, i.e. DAF or CD55, interaction of DAF with the convertases is mediated predominantly by two patches, one centered around Arg69 and Arg96 on CCP2 and the other around Phe148 and Leu171 on CCP3, structure, overview
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?
additional information
?
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the multi-domain serine protease C2 is the catalytic fragment of classical pathway C3 and C5 convertase of human complement of the classical and lectin pathways of complement activation, formation of these convertases requires the Mg2+-dependent binding of C2 to C4b and the subsequent cleavage of C2 by C1s or MASP2, respectively, the C-terminal fragment C2a consisting of a serine protease and a von Willebrand factor type A domain, remains attached to C4b, forming the C3 convertase, C4b2a, structure, overview
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?
additional information
?
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the virion-associated Kaposis sarcoma-associated herpesvirus complement control protein is required for complement regulation and cell binding, involved structures, Kaposis sarcoma-associated herpesvirus, KSHV, encodes a lytic cycle protein called KSHV complement control protein, KCP, that inhibits activation of the complement cascade. It does so by regulating C3 convertases, accelerating their decay, and acting as a cofactor for factor I degradation of C4b and C3b, two components of the C3 and C5 convertases, KCP is expressed on the surface of human infected endothelial cells, mechanism, overview, K64Q/K65Q/K88Q KCP mutant lacks complement regulatory activity
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?
additional information
?
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pharmacological complement inhibition at the C3 convertase level promotes neuronal survival, neuroprotective intracerebral gene expression, and neurological outcome after traumatic brain injury, overview
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?
additional information
?
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the enzyme catalyzes the central step of the complement cascade, overview, molecular interactions between MBL-associated serine protease-2, MASP-2, C4, and C2 and their activation fragments leading to complement activation via the lectin pathway, MASP-2 cleaves C4 releasing C4a and generating C4b, which attaches covalently to the pathogen surface upon exposure of its reactive thioester, C2 binds to C4b and is also cleaved by MASP-2 to form the C3 convertase C4b2a, overview
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-
?
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NATURAL SUBSTRATE
NATURAL PRODUCT
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate)
(Substrate)
LITERATURE
(Substrate)
(Substrate)
COMMENTARY
(Product)
(Product)
LITERATURE
(Product)
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
r=reversible
ir=irreversible
?=not specified
complement component C3 + H2O
?
-
classical pathway of the complement system
-
-
?
complement component C3 + H2O
component C3b + anaphylatoxin C3a
-
-
iC3b is generated by Factor I after formation of C3b. iC3b is a proteolytically inactive form of C3b that retains the ability to opsonize microbes, but cannot participate in convertase function
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
-
-
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
complement component C3 is the preferred substrate. Cleavage of the preferred C3 substrate and deposition of C3b effectively switches the output of the enzyme from C3b to C5b, resulting in initiation of the cytosolic process of complement
-
?
complement component C3 + H2O
complement component C3a + complement component C3b
-
C3 complement cleavage is a central event in the activation of the complement system via the classical, the alternative, and the lectin pathway, overview
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
-
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
C5 convertases C4b2aC3b and C3b 2 Bb
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
C5 convertases, C4b2a3b and C3b2Bb, cleave C5 into the anaphylatoxin C5a and C5b followed by initiation of the terminal pathway, leading to formation of lytic C5b-9 membrane attack complexes, overview
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
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C5 convertases, C4b2a3b and C3b2Bb, cleave C5 into the anaphylatoxin C5a and C5b, overview
-
-
?
complement component C5 + H2O
complement component C5a + complement component C5b
-
C5 convertases, C4b2a3b and C3b2Bb, cleave C5 into the anaphylatoxin C5a and C5b, overview
-
-
?
complement componentC3 + H2O
complement component C3a + complement component C3b
-
C3 convertase C3bBb
-
-
?
complement componentC3 + H2O
complement component C3a + complement component C3b
-
C3 convertases, C4b2a and C3bBb, cleave C3 into the anaphylatoxin C3a and C3b, overview
-
-
?
complement componentC3 + H2O
complement component C3a + complement component C3b
-
C3 convertases, C4b2a and C3bBb, cleave C3 into the anaphylatoxin C3a and C3b, overview
-
-
?
additional information
?
-
-
dissociation of the classical-complement-pathway C3/C5 convertase by the regulators decay-accelerating factor, DAF, complement receptor 1, CR1, factor H and C4-binding protein C4BP, controls the function of the enzyme. Decay acceleration mediated by DAF, C4BP and CR1 requires interaction of the alpha4/5 region of C2a with a CCP2/CCP3 site of DAF or structurally homologous sites of CR1 and C4BP
-
?
additional information
?
-
-
the enzyme has a very short half-life. Dissociation of the two noncovalently bound subunits proceeds with a half_life of 1-3 min at 37°C under physiological conditions, and this rate increases greatly if regulatory proteins are present. Numerous decay-accelerating proteins are present in plasma and on host cells that bind to the noncatalytic subunit C4b and increase the rate at which the catalytic subunit C2a is released into the medium. C2a loses its enzymatic activity and its ability to bind to C4b upon release. Although C4b is able to rebind C2 and reform the enzyme, the interaction with most decay-accelerating factors also leads to permanent proteolytic interaction of the cell-bound subunit C4b by a fluid-phase protease Factor I. Theses regulatory events limit cleavage of C3, reduce release of the anaphylatoxin C3a and control the formation of more efficient C5 convertase enzymes
-
?
additional information
?
-
-
factor B associates with complement component C3b and after proteolysis yields the C3 convertase of the alternative pathway, complement component C2A provides the catalytic center to the convertase complexes of the classical and lectin-binding pathways of complement activation, structural basis of the substrate specificity of the complement complex, overview, attachment of C3b to either C4b2a or C3bBb yields the C5 convertases, C4b2a3b and C3b2Bb, respectively, that cleave complement component C5
-
-
?
additional information
?
-
-
the alternative pathway lead via C3 convertase C3bBb and the C5 convertases C4b2aC3b and C3b 2 Bb
-
-
?
additional information
?
-
-
the C3 convertases, bimolecular complexes C4b2a and C3bBb, of the classical and alternative pathways are the central enzymes of the complement cascade, focused complement activation on foreign targets depends on regulatory proteins that decay the bimolecular C3 convertases, activity and regulation of complement control proteins CCP1-CCP4 as modules of the cell surface regulator, decay-accelerating factor, i.e. DAF or CD55, interaction of DAF with the convertases is mediated predominantly by two patches, one centered around Arg69 and Arg96 on CCP2 and the other around Phe148 and Leu171 on CCP3, structure, overview
-
-
?
additional information
?
-
-
the multi-domain serine protease C2 is the catalytic fragment of classical pathway C3 and C5 convertase of human complement of the classical and lectin pathways of complement activation, formation of these convertases requires the Mg2+-dependent binding of C2 to C4b and the subsequent cleavage of C2 by C1s or MASP2, respectively, the C-terminal fragment C2a consisting of a serine protease and a von Willebrand factor type A domain, remains attached to C4b, forming the C3 convertase, C4b2a, structure, overview
-
-
?
additional information
?
-
-
the virion-associated Kaposis sarcoma-associated herpesvirus complement control protein is required for complement regulation and cell binding, involved structures, Kaposis sarcoma-associated herpesvirus, KSHV, encodes a lytic cycle protein called KSHV complement control protein, KCP, that inhibits activation of the complement cascade. It does so by regulating C3 convertases, accelerating their decay, and acting as a cofactor for factor I degradation of C4b and C3b, two components of the C3 and C5 convertases, KCP is expressed on the surface of human infected endothelial cells, mechanism, overview, K64Q/K65Q/K88Q KCP mutant lacks complement regulatory activity
-
-
?
additional information
?
-
-
pharmacological complement inhibition at the C3 convertase level promotes neuronal survival, neuroprotective intracerebral gene expression, and neurological outcome after traumatic brain injury, overview
-
-
?
additional information
?
-
-
the enzyme catalyzes the central step of the complement cascade, overview, molecular interactions between MBL-associated serine protease-2, MASP-2, C4, and C2 and their activation fragments leading to complement activation via the lectin pathway, MASP-2 cleaves C4 releasing C4a and generating C4b, which attaches covalently to the pathogen surface upon exposure of its reactive thioester, C2 binds to C4b and is also cleaved by MASP-2 to form the C3 convertase C4b2a, overview
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-
?
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METALS and IONS
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
Ca2+
Mg2+
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INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
C4b-binding protein
-
regulates assembly and decay of the classical pathway C3/C5 convertase 4times lower than the lectin pathway convertase
-
CN-
-
inhibits the aggregation of C4b and C2a and the activity of the active enzyme
complement receptor of immunoglobulin family
-
inhibits C5 conversion specifically
-
complement receptor type 1-related protein y
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i.e. Crry, a mouse-specific complement inhibitor, expressed in astrocytes, microglia, and neurons of murine brain, in vivo and in vitro inhibition of C3 convertase, overview
-
eculizumab
-
potently inhibits C5 conversion but leaves C3 conversion unaffected
-
extracellular complement binding protein
-
does not inhibit C3 convertase activity but C5 convertase activity
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extracellular complement-binding protein
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Ecb, a potent complement inhibitor from Staphylococcus aureus, with strong antiinflammatory properties, inhibitory mechanism for blocking C3b-containing convertases, Efb-C and Ecb act on the bacterial surface, overview
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extracellular fibrinogen-binding protein
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Efb, a potent complement inhibitor from Staphylococcus aureus, with strong antiinflammatory properties, inhibitory mechanism for blocking C3b-containing convertases, Efb-C and Ecb act on the bacterial surface, overview
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factor H related-protein 5
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inhibits C5 conversion in a concentration-dependent manner
-
hepatitis virus C
-
inhibition of C3 convertase activity and C3b deposition onto bacterial membrane by hepatitis C virus, impairment of both C3 convertase and Factor I activity
-
N-terminal long homologous repeat A of complement receptor type 1
-
responsible for dissociation of enzyme. Highest decay accelerating activity for mutant dimeric construct N-terminal long homologous repeat A (D109N/E116K)/N-terminal long homologous repeat A (D109N)
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NH2-CD59-DAF-GPI
-
chimeric molecule, DAF: decay accelerating factor, GPI: glycosylphosphatidylinositol
-
NH2DAF-CD59-GPI
-
chimeric molecule, DAF: decay accelerating factor, GPI: glycosylphosphatidylinositol
-
OmCI
-
the inhibitor blocks C5 cleavage by interfering with convertase recognition far from C5a
-
Ornithodoros moubata complement inhibitory protein
-
potently inhibits C5 conversion but leaves C3 conversion unaffected
-
Pra1
-
i. e. Candida albicans complement regulator acquiring surface protein 2 or pH-regulated Ag 1. In the direct surrounding of the pathogen, inhibitor binds to fluid-phase C3, blocks cleavage of C3 to C3a and C3b and inhibits complement activation via the alternative and classical pathways. In addition, the release of the anaphylatoxins C3a and C5a, as well as C3b/iC3b surface deposition, is reduced. By reducing C3b/iC3b levels at the yeast surface, Pra1 decreases complement-mediated adhesion, as well as uptake of Candida albicans by human macrophages
-
SSL7
-
the inhibitor blocks C5 cleavage by interfering with convertase recognition far from C5a
-
staphylococcal complement inhibitor
-
SCIN, a potent complement inhibitor from Staphylococcus aureus, with strong antiinflammatory properties, inhibitory mechanism for blocking C3b-containing convertases, overview
-
thioredoxin 1
-
Trx-1, but not an active site mutated form, inhibits both C3 and C5 classical convertase formation, mechanism, overview. Trx-1 is capable of inhibiting all classical and alternative convertases but its effect is more pronounced in inhibition of alternative ones
additional information
-
Kaposi's sarcoma-associated herpesvirus complement control protein inhibits complement through decay-accelerating activity of the classical C3 convertase and cofactor activity for factor I-mediated degradtion of C4b and C3b, as well as acting as an attachment factor for binding to heparan sulfate on permissive cells, overview
-
additional information
-
the C3b-specific antibody fragment S77 does not inhibit the classical pathway C5 convertase in human serum
-
additional information
-
addition of guinea pig serum in 40 mM EDTA initiates lysis of existing convertase complexes and excludes the possibility of de novo convertase formation
-
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
C3b
-
both the soluble form of the enzyme, C4b,C2a and the surface-bound form of the enzyme EAC1,C4b,C2a exhibit a poor affinity for the substrate C5. Very high affinity C5 convertase is generated only when the low affinity C3/C5 convertases are allowed to deposit C3b by cleaving native C3
-
complement component C3b
-
in inactive surface-fixed form essential for cleavage of C5
-
factor B
-
the classical C5 convertase requires factor D, factor B, and properdin for activation and complex assembly
-
factor D
-
the classical C5 convertase requires factor D, factor B, and properdin for activation and complex assembly
-
properdin
-
the classical C5 convertase requires factor D, factor B, and properdin for activation and complex assembly
-
zymosan
-
it is capable of activating the classical pathway as well as the alternative pathway, when the classical pathway is blocked, mechanism, overview
-
additional information
-
cooperation of the enzyme with MBL-associated serine proteases MASP-1 and MASP-2 in C3 cleavage, the serine proteases generate active C3 convertase at high serum concentration, while MASP-3 inhibits it, overview
-
additional information
-
properdin can initiate complement activation by binding specific target surfaces, e.g. microbial targets like Neisseria gonorrhoeae, and Escherichia coli and Salmonella typhimurium lipopolysaccharide mutants, or yeast cell walls, , and providing a platform for de novo convertase assembly and function via the alternative pathway, overview, recombinant human compound
-
additional information
-
complement activation via the lectin pathway on zymosan particles is at least 4times more efficient than via the classical pathway on sheep erythrocytes coated with antibody. Every C4b deposited via the lectin pathway is capable of forming a convertase in contrast to only one of four C4b molecules deposited via the classical pathway. Rate of formation of lectin pathway C3/C5 convertases depends on the activation of C4 and C2 by MASP-2
-
additional information
-
molecular interactions between MASP-2, C4, and C2 and their activation fragments leading to complement activation via the lectin pathway, overview
-
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DISEASE
TITLE OF PUBLICATION
LINK TO PUBMED
Arthritis
The complement system is activated in synovial fluid from subjects with knee injury and from patients with osteoarthritis.
Arthritis, Rheumatoid
The complement system is activated in synovial fluid from subjects with knee injury and from patients with osteoarthritis.
Colitis
Regulation of the alternative pathway of complement modulates injury and immunity in a chronic model of dextran sulphate sodium-induced colitis.
Diabetic Nephropathies
Loss of decay-accelerating factor triggers podocyte injury and glomerulosclerosis.
Glomerulonephritis
Accelerated decay of the cell bound C4b2a complex by serum of patients with membranoproliferative glomerulonephritis and acute poststreptococcal glomerulonephritis.
Glomerulonephritis
Mechanism of action of the C4 nephritic factor. Deregulation of the classical pathway of C3 convertase.
Glomerulonephritis
Regulation and deregulation of the fluid-phase classical pathway C3 convertase.
Glomerulonephritis, Membranoproliferative
Accelerated decay of the cell bound C4b2a complex by serum of patients with membranoproliferative glomerulonephritis and acute poststreptococcal glomerulonephritis.
Glomerulonephritis, Membranoproliferative
Autoantibody to complement neoantigens in membranoproliferative glomerulonephritis.
Glomerulonephritis, Membranoproliferative
Autoimmune forms of thrombotic microangiopathy and membranoproliferative glomerulonephritis: Indications for a disease spectrum and common pathogenic principles.
Infections
Regulation of the alternative pathway of complement modulates injury and immunity in a chronic model of dextran sulphate sodium-induced colitis.
Lupus Erythematosus, Systemic
Heterogeneity, polypeptide chain composition and antigenic reactivity of autoantibodies (F-42) that are directed against the classical pathway C3 convertase of complement and isolated from sera of patients with systemic lupus erythematosus.
Lupus Erythematosus, Systemic
Relative importance of C4 binding protein in the modulation of the classical pathway C3 convertase in patients with systemic lupus erythematosus.
Lupus Erythematosus, Systemic
Stabilization of the classical pathway C3 convertase C42, by a factor F-42, isolated from serum of patients with systemic lupus erythematosus.
Multiple Sclerosis
A systematic analysis of the complement pathways in patients with neuromyelitis optica indicates alteration but no activation during remission.
Neoplasms
The complement system is activated in synovial fluid from subjects with knee injury and from patients with osteoarthritis.
Sepsis
Autoantibody stabilization of the classical pathway C3 convertase leading to C3 deficiency and Neisserial sepsis: C4 nephritic factor revisited.
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.0000011 - 0.0000083
complement component C5
-
37°C, high-affinity C5 convertase EAC1,C3bC4b,C2a
-
0.0000051
complement component C5
-
high affinity C5 convertase (EAC1,C3bC4b,C2a)
-
0.0046 - 0.0066
complement component C5
-
37°C, surface bound C3/C5 convertase, EAC1,C4b,C2a
-
0.0089
complement component C5
-
37°C, soluble monomeric C3/C5 convertase C4b,C2a
-
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.015 - 0.026
complement component C5
-
37°C, high-affinity C5 convertase EAC1,C3bC4b,C2a
-
0.022
complement component C5
-
37°C, soluble monomeric C3/C5 convertase C4b,C2a
-
0.023 - 0.047
complement component C5
-
37°C, surface bound C3/C5 convertase, EAC1,C4b,C2a
-
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IC50 VALUE [mM]
INHIBITOR
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
IMAGE
0.00025
soluble complement receptor type 1
Homo sapiens
-
at 37°C, pH not specified in the publication
-
0.000005
C4b-binding protein
Ovis aries
-
IC50 for the inhibition of formation of soluble C3 convertase (C4b,C2a)
-
0.000011
C4b-binding protein
Ovis aries
-
IC50 for the acceleration of decay of surface-bound C3 convertase (EAC1,C4b,C2a)
-
0.000017
C4b-binding protein
Ovis aries
-
IC50 for the acceleration of decay of soluble C3 convertase (C4b,C2a)
-
0.00002
C4b-binding protein
Ovis aries
-
IC50 for the acceleration of decay of high affinity C5 convertase (EAC1,C3bC4b,C2a)
-
0.000035
C4b-binding protein
Ovis aries
-
IC50 for the inhibition of formation of surface-bound C3 convertase (EAC1,C4b,C2a)
-
0.000072
C4b-binding protein
Ovis aries
-
IC50 for the inhibition of formation of high affinity C5 convertase (EAC1,C3bC4b,C2a)
-
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pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
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TEMPERATURE OPTIMUM
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
37
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ORGANISM
COMMENTARY
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
-
81407, 81408, 81410, 81411, 81412, 81413, 81414, 81415, 649815, 652460, 652494, 653251, 669726, 680169, 683532, 683646, 683716, 683737, 683775, 683831, 684068, 695326, 698871, 709002, 710434
-
-
brenda
2 distinct C3 convertases generated by 2 seperate enzyme cascade systems
-
-
brenda
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SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
SOURCE
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LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY
GeneOntology No.
LITERATURE
SOURCE
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GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY
LITERATURE
malfunction
-
inhibition of C3 convertase activity by hepatitis C virus as an additional lesion in the regulation of complement components. Inhibition of C3 convertase activity and C3b deposition onto bacterial membrane by hepatitis C virus, impairment of both C3 convertase and Factor I activity, overview
metabolism
physiological function
additional information
-
the classical C5 convertase requires factor D, factor B, and properdin for activation and complex assembly
metabolism
-
all pathways converge at the level of the C3 molecule, where downstream events can be amplified by a mechanism of positive feedback supported by complement convertases: the classical/lectin pathway C3 convertase (C4b2a) or the alternative pathway C3 convertase (C3bBb). These convertases further cleave C3 to C3b and C3a, of which C3b binds to nearby surfaces, providing a convertase assembly platform, or to pre-assembled C3 convertases, switching them to C5 convertases (C4b2aC3b or C3bBbC3b, respectively). The C5 convertase cleaves C5 molecules to C5a and C5b and the latter initiates formation of the membrane attack complex (MAC, C5b678polyC9) and its insertion into a target membrane. Enzyme regulation, overview