X-ray diffraction
4Å resolution

Crystal Structure of Complement C3b in Complex with Factor B


Function and Biology Details

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.
Biochemical function:
Biological process:
Cellular component:

Structure analysis Details

Assembly composition:
hetero trimer (preferred)
Entry contents:
3 distinct polypeptide molecules
Macromolecules (3 distinct):
Complement C3 beta chain Chains: A, C, E, G
Molecule details ›
Chains: A, C, E, G
Length: 645 amino acids
Theoretical weight: 71.39 KDa
Source organism: Homo sapiens
  • Canonical: P01024 (Residues: 23-667; Coverage: 39%)
Gene names: C3, CPAMD1
Sequence domains:
Structure domains:
Complement C3b alpha' chain Chains: B, D, F, H
Complement factor B Chains: I, J, K, L
Molecule details ›
Chains: I, J, K, L
Length: 741 amino acids
Theoretical weight: 83.19 KDa
Source organism: Homo sapiens
Expression system: Homo sapiens
  • Canonical: P00751 (Residues: 26-764; Coverage: 100%)
Gene names: BF, BFD, CFB
Sequence domains:
Structure domains:

Ligands and Environments

2 bound ligands:

No modified residues

Experiments and Validation Details

Entry percentile scores
X-ray source: ESRF BEAMLINE ID14-4
Spacegroup: C2221
Unit cell:
a: 262.16Å b: 297.87Å c: 341.44Å
α: 90° β: 90° γ: 90°
R R work R free
0.23 0.228 0.281
Expression system: Homo sapiens