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Literature summary extracted from
- Mutations in complement factor I as found in atypical hemolytic uremic syndrome lead to either altered secretion or altered function of factor I (2010), Eur. J. Immunol., 40, 172-185.
Cloned(Commentary)
| EC Number | Cloned (Comment) | Organism |
|---|---|---|
| 3.4.21.45 | cloned into the eukaryotic expression vector pcDNA3 with addition of an N-terminal His-tag and transiently expressed in human embryonic kidney 293 cells | Homo sapiens |
| 3.4.21.45 | expressed as an N-terminal His-tagged fusion protein in human embryonic kidney cells | Homo sapiens |
Protein Variants
| EC Number | Protein Variants | Comment | Organism |
|---|---|---|---|
| 3.4.21.45 | A222G | secretion of mutant protein significantly lower compared to wild-type when expressed in human embryonic kidney cells. Mutant cleaves the alpha'-chains of complement factor C4b and C3b as efficiently as wild-type in solution. Compared to wild-type mutant A22G shows impaired cleavage of complement factor C3b on the surface of sheep erythrocytes. Mutant cleaves C3b alpha'chain on the surface of endothelial cells (HUVEV-cells) as efficiently as wild-type | Homo sapiens |
| 3.4.21.45 | C25F | mutant is as efficiently expressed in human embryonic kidney cells as wild-type, mutant protein is not secreted. Mutant is sensitive to EndoH digestion, indicating that it does not reach the late Golgi compartment and is retained in the endoplasmic reticulum | Homo sapiens |
| 3.4.21.45 | D207N/Q219A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | D207N/Q219A/M220A/K221Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | D26N/K27Q/F29A/Q31A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) similar to wild-type, Vmax significantly increased compared to wild-type. Compared to wild-type mutant shows strongly impaired activity in degradation of fluid-phase complement factor C4b or C3b and in the degradation of surface-bound C3b deposited on sheep erythrocytes | Homo sapiens |
| 3.4.21.45 | D501N | mutant is as efficiently expressed and secreted in human embryonic kidney cells as wild-type, mutant does not degrade complement factor C4b or C3b. In contrast to wild-type mutant D501N does not cleave C3b alpha'chain on the surface of endothelial cells (HUVEV-cells) | Homo sapiens |
| 3.4.21.45 | F29A/Q31A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) similar to wild-type, Vmax significantly increased compared to wild-type. Compared to wild-type mutant shows strongly impaired activity in degradation of fluid-phase complement factor C4b or C3b | Homo sapiens |
| 3.4.21.45 | F94A/K182Q/R184Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) similar to wild-type, Vmax significantly increased compared to wild-type. Compared to wild-type mutant shows strongly impaired activity in degradation of fluid-phase complement factor C4b or C3b. Mutant shows greatly impaired activity in the degradation of surface-bound C3b deposited on sheep erythrocytes | Homo sapiens |
| 3.4.21.45 | H165R | mutant is as efficiently expressed and secreted in human embryonic kidney cells as wild-type. Mutant cleaves the alpha'-chains of complement factor C4b and C3b more efficiently than wild-type in the presence of C4b-binding protein and factor H as cofactors in solution. Cleavage of complement factor C3b on the surface of sheep erythrocytes is similar to wild-type. In the presence of membrane cofactor protein mutant cleaves C3b alpha'chain on the surface of endothelial cells (HUVEV-cells) more efficiently than wild-type | Homo sapiens |
| 3.4.21.45 | K124Q/R150Q/F151A/K152Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | K182Q/R184Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type. Mutant shows similar activity to wild-type in degradation of fluid-phase complement factor C4b or C3b and in the degradation of surface-bound C3b deposited on sheep erythrocytes | Homo sapiens |
| 3.4.21.45 | K51A/R62A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type, only mutant in the FI and membrane attack complex domain (FIMAC) which shows some activity in degradation of fluid-phase complement factor C4b or C3b | Homo sapiens |
| 3.4.21.45 | K51A/R62A/L73A/L76A/F82A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | K93Q/F94A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type. Compared to wild-type mutant shows decreased but not abolished activity in degradation of fluid-phase complement factor C4b or C3b. Mutant shows impaired activity in the degradation of surface-bound C3b deposited on sheep erythrocytes | Homo sapiens |
| 3.4.21.45 | L289x | deletion mutant (c.893delC) leading to a premature stop codon. Mutant protein is not secreted when expressed in human embryonic kidney cells | Homo sapiens |
| 3.4.21.45 | L73A/L76A/F82A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | M120V | mutant is as efficiently expressed in human embryonic kidney cells as wild-type, secretion is significantly lower compared to wild-type. Mutant cleaves the alpha'-chains of complement factor C4b and C3b more efficiently than wild-type in the presence of C4b-binding protein and factor H as cofactors in solution. Mutant cleaves complement factor C3b more efficiently in the presence of membrane cofactor protein in solution. Compared to wild-type mutant M120V shows enhanced cleavage of complement factor C3b on the surface of sheep erythrocytes. In the presence of membrane cofactor protein mutant cleaves C3b alpha'chain on the surface of endothelial cells (HUVEV-cells) more efficiently than wild-type | Homo sapiens |
| 3.4.21.45 | M220A/K221Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | N133S | mutant protein is not secreted when expressed in human embryonic kidney cells, mutant is sensitive to EndoH digestion, indicating that it does not reach the late Golgi compartment and is retained in the endoplasmic reticulum | Homo sapiens |
| 3.4.21.45 | P32A | mutant is as efficiently expressed and secreted in human embryonic kidney cells as wild-type. P32A mutant shows impaired function towards degradation of the alpha'-chains of complement factor C4b at the two highest concentrations and of the alpha'-chain of C3b at the highest concentration when factor H is used as cofactor. No significant impairment when complement receptor 1 and membrane cofactor protein 1 are used as cofactors. Compared to wild-type mutant P32A shows impaired cleavage of complement factor C3b on the surface of sheep erythrocytes. Mutant cleaves C3b alpha'chain on the surface of endothelial cells (HUVEV-cells) as efficiently as wild-type | Homo sapiens |
| 3.4.21.45 | R130Q/R169Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | R150Q/F151A/K152Q | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) and Vmax similar to wild-type | Homo sapiens |
| 3.4.21.45 | R299W | mutant is as efficiently expressed in human embryonic kidney cells as wild-type, secretion is significantly lower compared to wild-type. Mutant cleaves the alpha'-chains of complement factor C4b and C3b as efficiently as wild-type in solution. Cleavage of complement factor C3b on the surface of sheep erythrocytes is similar to wild-type. In the presence of membrane cofactor protein mutant cleaves C3b alpha'chain on the surface of endothelial cells (HUVEV-cells) more efficiently than wild-type | Homo sapiens |
| 3.4.21.45 | R456x | point mutant leading to a premature stop codon. Mutant protein is not secreted when expressed in human embryonic kidney cells | Homo sapiens |
| 3.4.21.45 | T520x | insertion mutant (c. 1610insAT) leading to a premature stop codon, mutant protein is not secreted when expressed in human embryonic kidney cells | Homo sapiens |
| 3.4.21.45 | V212A/L236A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) similar to wild-type, Vmax significantly increased compared to wild-type. Compared to wild-type mutant shows strongly impaired activity in degradation of fluid-phase complement factor C4b or C3b. Mutant shows no activity in the degradation of surface-bound C3b deposited on sheep erythrocytes | Homo sapiens |
| 3.4.21.45 | V252A/I267A | Km (tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin) similar to wild-type, Vmax significantly increased compared to wild-type. Compared to wild-type mutant shows strongly impaired activity in degradation of fluid-phase complement factor C4b or C3b. Mutant shows no activity in the degradation of surface-bound C3b deposited on sheep erythrocytes | Homo sapiens |
| 3.4.21.45 | W127X | point mutant leading to a premature stop codon. Mutant protein is not secreted when expressed in human embryonic kidney cells | Homo sapiens |
| 3.4.21.45 | W468x | deletion mutant (c.1446-1450 delTTCAC) leading to a premature stop codon, mutant is as efficiently expressed in human embryonic kidney cells as wild-type but protein is not secreted | Homo sapiens |
| 3.4.21.45 | W528x | point mutant leading to a premature stop codon. Mutant protein is not secreted when expressed in human embryonic kidney cells | Homo sapiens |
KM Value [mM]
| EC Number | KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|---|
| 3.4.21.45 | 0.041 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant K182Q/R184Q, Vmax: 0.058 pmol/min/microgram protein | Homo sapiens |  |
| 3.4.21.45 | 0.0508 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant M220A/K221Q, Vmax: 0.01 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.054 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant K51A/R62A/L73A/L76A/F82A, Vmax: 0.085 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.074 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant K93Q/F94A, Vmax: 0.147 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.083 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant L73A/L76A/F82A, Vmax: 0.053 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.103 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant R130Q/R169Q, Vmax: 0.16 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.112 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant K124Q/R150Q/F151A/K152Q, Vmax: 0.1 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.114 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant D207N/Q219A, Vmax: 0.044 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.121 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant V252A/I267A, Vmax: 1.284 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.122 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant R150Q/F151A/K152Q, Vmax: 0.087 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.14 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant D26N/K27Q/F29A/Q31A, Vmax: 0.834 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.149 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | wild-type, Vmax: 0.09 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.168 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant F94A/K182Q/R184Q, Vmax: 0.672 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.177 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant K51A/R62A, Vmax: 0.373 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.195 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant D207N/Q219A/M220A/K221Q, Vmax: 0.032 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.199 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant F29A/Q31A, Vmax: 0.854 pmol/min/microgram protein | Homo sapiens | |
| 3.4.21.45 | 0.203 | - |
tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin | mutant V212A/L236A, Vmax: 2.126 pmol/min/microgram protein | Homo sapiens | |
Localization
| EC Number | Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|---|
| 3.4.21.45 | endoplasmic reticulum | upon EndoH digestion, a large fraction of wild-type complement factor I is EndoH sensitive and displays faster mobility upon electrophoresis representing protein in endoplasmic reticulum still undergoing processing, but significant amount of wild-type complement factor I is resistant to EndoH indicates transport to late secretory compartments and beyond | Homo sapiens | 5783 | - |
| 3.4.21.45 | secretory vesicle | upon EndoH digestion, a large fraction of wild-type complement factor I is EndoH sensitive and displays faster mobility upon electrophoresis representing protein in endoplasmic reticulum still undergoing processing, but significant amount of wild-type complement factor I is resistant to EndoH indicates transport to late secretory compartments and beyond | Homo sapiens | 99503 | - |
Molecular Weight [Da]
| EC Number | Molecular Weight [Da] | Molecular Weight Maximum [Da] | Comment | Organism |
|---|---|---|---|---|
| 3.4.21.45 | 38000 | - |
light-chain, Western blot, reducing condition | Homo sapiens |
| 3.4.21.45 | 50000 | - |
heavy-chain, Western blot, reducing condition | Homo sapiens |
| 3.4.21.45 | 88000 | - |
SDS-PAGE, non-reducing conditions | Homo sapiens |
| 3.4.21.45 | 88000 | - |
Western blot, non-reducing condition | Homo sapiens |
Organism
| EC Number | Organism | UniProt | Comment | Textmining |
|---|---|---|---|---|
| 3.4.21.45 | Homo sapiens | - |
- |
- |
Purification (Commentary)
| EC Number | Purification (Comment) | Organism |
|---|---|---|
| 3.4.21.45 | using Ni-NTA chromatography | Homo sapiens |
Substrates and Products (Substrate)
| EC Number | Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|---|
| 3.4.21.45 | complement component C3b + H2O | - |
Homo sapiens | ? | - |
? | |
| 3.4.21.45 | complement component C4b + H2O | - |
Homo sapiens | ? | - |
? | |
| 3.4.21.45 | complement factor C3b + H2O | - |
Homo sapiens | ? | - |
? | |
| 3.4.21.45 | complement factor C4b + H2O | - |
Homo sapiens | ? | - |
? | |
| 3.4.21.45 | tert-butyloxycarbonyl-Asp(benzyl)-Pro-Arg-7-amido-4-methylcoumarin + H2O | - |
Homo sapiens | ? | - |
? | |
Synonyms
| EC Number | Synonyms | Comment | Organism |
|---|---|---|---|
| 3.4.21.45 | complement factor I | - |
Homo sapiens |
Temperature Optimum [°C]
| EC Number | Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|---|
| 3.4.21.45 | 37 | - |
assay at | Homo sapiens |
pH Optimum
| EC Number | pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|---|
| 3.4.21.45 | 8.25 | - |
assay at | Homo sapiens |
Cofactor
| EC Number | Cofactor | Comment | Organism | Structure |
|---|---|---|---|---|
| 3.4.21.45 | additional information | complement factor C3b and C4b are degraded in the presence of cofactors factor H, C4b-binding protein (C4BP), membrane cofactor protein (MCP) and complement receptor (CR1), respectively | Homo sapiens | |
| 3.4.21.45 | additional information | for cleavage of complement factor C3b or C4b, complement factor I is mixed with C4b-binding protein or membrane cofactor protein or complement receptor 1 or factor H | Homo sapiens |
General Information
| EC Number | General Information | Comment | Organism |
|---|---|---|---|
| 3.4.21.45 | malfunction | mutations in complement factor I affect both secretion and function of complement factor I, which leads to impaired regulation of the complement system in atypical hemolytic uremic syndrome | Homo sapiens |
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