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Human complement factor I

Source organism: Homo sapiens
Biochemical function: metal ion binding
Biological process: innate immune response
Cellular component: extracellular exosome

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EC 3.4.21.45: Complement factor I

Reaction catalysed:
Inactivates complement subcomponents C3b, iC3b and C4b by proteolytic cleavage.
Systematic name:
-
Alternative Name(s):
  • C3b inactivator
  • C3b/C4b inactivator
  • C3bINA
  • Complement C3b inactivator
  • Complement C3b/C4b inactivator
  • Complement C4b inactivator
  • Complement C4bi
  • Complement component C3b inactivator
  • Conglutinogen-activating factor C
  • Factor I

GO terms

Sequence families

Pfam Protein families (Pfam)
PF00057
Domain description: Low-density lipoprotein receptor domain class A
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 8 copies of Pfam domain PF00057 (Low-density lipoprotein receptor domain class A) in Complement factor I. Showing 2 copies in chain B.

PF00089
Domain description: Trypsin
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of Pfam domain PF00089 (Trypsin) in Complement factor I. Showing 1 copy in chain B.

PF00530
Domain description: Scavenger receptor cysteine-rich domain
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of Pfam domain PF00530 (Scavenger receptor cysteine-rich domain) in Complement factor I. Showing 1 copy in chain B.

PF21287
Domain description: Complement factor I, KAZAL domain
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of Pfam domain PF21287 (Complement factor I, KAZAL domain) in Complement factor I. Showing 1 copy in chain B.

PF21286
Domain description: Complement factor I, FIMAC N-terminal domain
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of Pfam domain PF21286 (Complement factor I, FIMAC N-terminal domain) in Complement factor I. Showing 1 copy in chain B.

InterPro InterPro annotations
IPR002172
Domain description: Low-density lipoprotein (LDL) receptor class A repeat
Occurring in:
  1. Complement factor I
IPR001254
Domain description: Serine proteases, trypsin domain
Occurring in:
  1. Complement factor I
IPR036055
Domain description: LDL receptor-like superfamily
Occurring in:
  1. Complement factor I
IPR001314
Domain description: Peptidase S1A, chymotrypsin family
Occurring in:
  1. Complement factor I
IPR001190
Domain description: SRCR domain
Occurring in:
  1. Complement factor I
IPR036772
Domain description: SRCR-like domain superfamily
Occurring in:
  1. Complement factor I
IPR033116
Domain description: Serine proteases, trypsin family, serine active site
Occurring in:
  1. Complement factor I
IPR018114
Domain description: Serine proteases, trypsin family, histidine active site
Occurring in:
  1. Complement factor I
IPR043504
Domain description: Peptidase S1, PA clan, chymotrypsin-like fold
Occurring in:
  1. Complement factor I
IPR009003
Domain description: Peptidase S1, PA clan
Occurring in:
  1. Complement factor I
IPR023415
Domain description: Low-density lipoprotein (LDL) receptor class A, conserved site
Occurring in:
  1. Complement factor I
IPR017448
Domain description: SRCR-like domain
Occurring in:
  1. Complement factor I
IPR002350
Domain description: Kazal domain
Occurring in:
  1. Complement factor I
IPR036058
Domain description: Kazal domain superfamily
Occurring in:
  1. Complement factor I
IPR003884
Domain description: Factor I / membrane attack complex
Occurring in:
  1. Complement factor I

Structure domains

CATH CATH domains
2.40.10.10
Class: Mainly Beta
Architecture: Beta Barrel
Topology: Thrombin, subunit H
Homology: Trypsin-like serine proteases
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of CATH domain 2.40.10.10 (Thrombin, subunit H) in Complement factor I. Showing 1 copy in chain B.
3.10.250.10
Class: Alpha Beta
Architecture: Roll
Topology: Mac-2 Binding Protein
Homology: SRCR-like domain
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of CATH domain 3.10.250.10 (Mac-2 Binding Protein) in Complement factor I. Showing 1 copy in chain B.
3.30.60.30
Class: Alpha Beta
Architecture: 2-Layer Sandwich
Topology: Wheat Germ Agglutinin (Isolectin 2); domain 1
Homology: Wheat Germ Agglutinin (Isolectin 2); domain 1
Occurring in:
  1. Complement factor I
The deposited structure of PDB entry 2xrc contains 4 copies of CATH domain 3.30.60.30 (Wheat Germ Agglutinin (Isolectin 2); domain 1) in Complement factor I. Showing 1 copy in chain B.

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