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Crystal Structure of Human Complement C3b in Complex with MCP (CCP1-4)

Source organism: Homo sapiens
Biochemical function: endopeptidase inhibitor activity
Biological process: not assigned
Cellular component: extracellular space

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EC 3.4.21.47: Alternative-complement-pathway C3/C5 convertase

Reaction catalysed:
Cleavage of Arg-|-Ser bond in complement component C3 alpha-chain to yield C3a and C3b, and Arg-|- bond in complement component C5 alpha-chain to yield C5a and C5b.
Alternative Name(s):
  • (C3b)(n),Bb
  • (CVF)-dependent glycine-rich-beta-glucoprotein
  • Alternative complement pathway C3(C5) convertase
  • C3 convertase
  • C3 proactivator
  • C3b,Bb,CVF,Bb,C5 convertase
  • C5 convertase
  • CVF,Bb
  • Cobra venom factor-dependent C3 convertase
  • Complement C 3(C 5) convertase (amplification)
  • Complement component C3/C5 convertase (alternative)
  • Complement factor B
  • Glycine-rich beta-glycoprotein
  • Heat-labile factor
  • Proenzyme factor B
  • Properdin factor B

GO terms

Biochemical function:
Biological process:
  • not assigned
Cellular component:

Sequence families

Pfam Protein families (Pfam)
PF00084
Domain description: Sushi repeat (SCR repeat)
Occurring in:
  1. Membrane cofactor protein
The deposited structure of PDB entry 5fo8 contains 4 copies of Pfam domain PF00084 (Sushi repeat (SCR repeat)) in Membrane cofactor protein. Showing 4 copies in chain C (some of the copies are out of the observed residue ranges!).

PF01759
Domain description: UNC-6/NTR/C345C module
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF01759 (UNC-6/NTR/C345C module) in Complement C3b alpha' chain. Showing 1 copy in chain B.

PF07677
Domain description: A-macroglobulin receptor binding domain
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF07677 (A-macroglobulin receptor binding domain) in Complement C3b alpha' chain. Showing 1 copy in chain B.

PF21308
Domain description: Complement component 3, CUB domain 2
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF21308 (Complement component 3, CUB domain 2) in Complement C3b alpha' chain. Showing 1 copy in chain B.

PF07678
Domain description: A-macroglobulin TED domain
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF07678 (A-macroglobulin TED domain) in Complement C3b alpha' chain. Showing 1 copy in chain B.

PF21406
Domain description: Complement component 3, CUB domain 1
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF21406 (Complement component 3, CUB domain 1) in Complement C3b alpha' chain. Showing 1 copy in chain B.

PF00207
Domain description: Alpha-2-macroglobulin family
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF00207 (Alpha-2-macroglobulin family) in Complement C3b alpha' chain. Showing 1 copy in chain B.

PF07703
Domain description: Alpha-2-macroglobulin bait region domain
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF07703 (Alpha-2-macroglobulin bait region domain) in Complement C3 beta chain. Showing 1 copy in chain A.

PF17789
Domain description: Macroglobulin domain MG4
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF17789 (Macroglobulin domain MG4) in Complement C3 beta chain. Showing 1 copy in chain A.

PF17791
Domain description: Macroglobulin domain MG3
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF17791 (Macroglobulin domain MG3) in Complement C3 beta chain. Showing 1 copy in chain A.

PF01835
Domain description: MG2 domain
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF01835 (MG2 domain) in Complement C3 beta chain. Showing 1 copy in chain A.

PF17790
Domain description: Macroglobulin domain MG1
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of Pfam domain PF17790 (Macroglobulin domain MG1) in Complement C3 beta chain. Showing 1 copy in chain A.

InterPro InterPro annotations
IPR000436
Domain description: Sushi/SCR/CCP domain
Occurring in:
  1. Membrane cofactor protein
IPR035976
Domain description: Sushi/SCR/CCP superfamily
Occurring in:
  1. Membrane cofactor protein
IPR018933
Domain description: Netrin module, non-TIMP type
Occurring in:
  1. Complement C3b alpha' chain
IPR008993
Domain description: Tissue inhibitor of metalloproteinases-like, OB-fold
Occurring in:
  1. Complement C3b alpha' chain
IPR009048
Domain description: Alpha-macroglobulin, receptor-binding
Occurring in:
  1. Complement C3b alpha' chain
IPR036595
Domain description: Alpha-macroglobulin, receptor-binding domain superfamily
Occurring in:
  1. Complement C3b alpha' chain
IPR013783
Domain description: Immunoglobulin-like fold
Occurring in:
  1. Complement C3 beta chain
  2. Complement C3b alpha' chain
IPR001134
Domain description: Netrin domain
Occurring in:
  1. Complement C3b alpha' chain
IPR035815
Domain description: Complement C3-like, NTR domain
Occurring in:
  1. Complement C3b alpha' chain
IPR019742
Domain description: Alpha-2-macroglobulin, conserved site
Occurring in:
  1. Complement C3b alpha' chain
IPR047565
Domain description: Alpha-macroglobulin-like, thiol-ester bond-forming region
Occurring in:
  1. Complement C3b alpha' chain
IPR008930
Domain description: Terpenoid cyclases/protein prenyltransferase alpha-alpha toroid
Occurring in:
  1. Complement C3b alpha' chain
IPR011626
Domain description: Alpha-macroglobulin-like, TED domain
Occurring in:
  1. Complement C3b alpha' chain
IPR001599
Domain description: Alpha-2-macroglobulin
Occurring in:
  1. Complement C3b alpha' chain
IPR011625
Domain description: Alpha-2-macroglobulin, bait region domain
Occurring in:
  1. Complement C3 beta chain
IPR040839
Domain description: Macroglobulin domain MG4
Occurring in:
  1. Complement C3 beta chain
IPR041555
Domain description: Macroglobulin domain MG3
Occurring in:
  1. Complement C3 beta chain
IPR002890
Domain description: Macroglobulin domain
Occurring in:
  1. Complement C3 beta chain
IPR041425
Domain description: Complement C3/4/5, macroglobulin domain MG1
Occurring in:
  1. Complement C3 beta chain

Structure domains

CATH CATH domains
2.60.40.1930
Class: Mainly Beta
Architecture: Sandwich
Topology: Immunoglobulin-like
Homology: Immunoglobulin-like
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 3 copies of CATH domain 2.60.40.1930 (Immunoglobulin-like) in Complement C3 beta chain. Showing 3 copies in chain A.
2.10.70.10
Class: Mainly Beta
Architecture: Ribbon
Topology: Complement Module; domain 1
Homology: Complement Module, domain 1
Occurring in:
  1. Membrane cofactor protein
The deposited structure of PDB entry 5fo8 contains 2 copies of CATH domain 2.10.70.10 (Complement Module; domain 1) in Membrane cofactor protein. Showing 2 copies in chain C.
2.60.120.1540
Class: Mainly Beta
Architecture: Sandwich
Topology: Jelly Rolls
Homology: Jelly Rolls
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.60.120.1540 (Jelly Rolls) in Complement C3b alpha' chain. Showing 1 copy in chain B.
2.60.40.10
Class: Mainly Beta
Architecture: Sandwich
Topology: Immunoglobulin-like
Homology: Immunoglobulins
Occurring in:
  1. Complement C3 beta chain
  2. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.60.40.10 (Immunoglobulin-like) in Complement C3 beta chain. Showing 1 copy in chain A.
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.60.40.10 (Immunoglobulin-like) in Complement C3b alpha' chain. Showing 1 copy in chain B.
2.40.50.120
Class: Mainly Beta
Architecture: Beta Barrel
Topology: OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Homology: OB fold (Dihydrolipoamide Acetyltransferase, E2P)
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.40.50.120 (OB fold (Dihydrolipoamide Acetyltransferase, E2P)) in Complement C3b alpha' chain. Showing 1 copy in chain B.
2.60.40.690
Class: Mainly Beta
Architecture: Sandwich
Topology: Immunoglobulin-like
Homology: Alpha-macroglobulin, receptor-binding domain
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.60.40.690 (Immunoglobulin-like) in Complement C3b alpha' chain. Showing 1 copy in chain B.
1.50.10.20
Class: Mainly Alpha
Architecture: Alpha/alpha barrel
Topology: Glycosyltransferase
Homology: Glycosyltransferase
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 1.50.10.20 (Glycosyltransferase) in Complement C3b alpha' chain. Showing 1 copy in chain B.
2.20.130.20
Class: Mainly Beta
Architecture: Single Sheet
Topology: S-adenosyl-L-methionine-dependent methyltransferases
Homology: S-adenosyl-L-methionine-dependent methyltransferases
Occurring in:
  1. Complement C3b alpha' chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.20.130.20 (S-adenosyl-L-methionine-dependent methyltransferases) in Complement C3b alpha' chain. Showing 1 copy in chain B.
6.20.50.160
Class: Special
Architecture: Other non-globular
Topology: N-terminal domain of TfIIb
Homology: N-terminal domain of TfIIb
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 6.20.50.160 (N-terminal domain of TfIIb) in Complement C3 beta chain. Showing 1 copy in chain A.
2.60.40.1940
Class: Mainly Beta
Architecture: Sandwich
Topology: Immunoglobulin-like
Homology: Immunoglobulin-like
Occurring in:
  1. Complement C3 beta chain
The deposited structure of PDB entry 5fo8 contains 1 copy of CATH domain 2.60.40.1940 (Immunoglobulin-like) in Complement C3 beta chain. Showing 1 copy in chain A.

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