› 8w18

X-ray diffraction
3.94Å resolution

The crystal structure of the Michaelis-Menten complex of a C1s/C1-INH at 3.94 Angstroms

Released:
DOI: 10.2210/pdb8w18/pdb
PDB entry 8w18 coloured by chain, front view.
PDB entry 8w18 coloured by chain, side view.
PDB entry 8w18 coloured by chain, top view.
Source organism: Homo sapiens
Primary publication:
The Crystal Structure of the Michaelis-Menten Complex of C1 Esterase Inhibitor and C1s Reveals Novel Insights into Complement Regulation.
Garrigues RJ, Garrison MP, Garcia BL
J Immunol (2024)
PMID: 38995166

Function and Biology Details

Reaction catalysed: 
Cleavage of Arg-|-Ala bond in complement component C4 to form C4a and C4b, and Lys(or Arg)-|-Lys bond in complement component C2 to form C2a and C2b: the 'classical' pathway C3 convertase.
Biochemical function:
Biological process:
Cellular component:

Structure analysis Details

Assembly composition:
hetero trimer (preferred)
Assembly name:
PDBe Complex ID:
PDB-CPX-272318 (preferred)
Entry contents:
3 distinct polypeptide molecules
Macromolecules (3 distinct):
Plasma protease C1 inhibitor Chain: I
Molecule details ›
Chain: I
Length: 395 amino acids
Theoretical weight: 44 KDa
Source organism: Homo sapiens
Expression system: Escherichia coli
UniProt:
  • Canonical: P05155 (Residues: 111-500; Coverage: 82%)
Gene names: C1IN, C1NH, SERPING1
Sequence domains: Serpin (serine protease inhibitor)
Complement C1s subcomponent light chain Chain: B
Molecule details ›
Chain: B
Length: 251 amino acids
Theoretical weight: 27.67 KDa
Source organism: Homo sapiens
Expression system: Escherichia coli
UniProt:
  • Canonical: P09871 (Residues: 438-688; Coverage: 37%)
Gene name: C1S
Sequence domains: Trypsin
Complement C1s subcomponent heavy chain Chain: A
Molecule details ›
Chain: A
Length: 151 amino acids
Theoretical weight: 16.59 KDa
Source organism: Homo sapiens
Expression system: Escherichia coli
UniProt:
  • Canonical: P09871 (Residues: 292-437; Coverage: 22%)
Gene name: C1S
Sequence domains: Sushi repeat (SCR repeat)

Ligands and Environments

No bound ligands
No modified residues

Experiments and Validation Details

Entry percentile scores
X-ray source: ALS BEAMLINE 5.0.2
Spacegroup: P42212
Unit cell:
a: 168.628Å b: 168.628Å c: 88.342Å
α: 90° β: 90° γ: 90°
R-values:
R R work R free
0.264 0.262 0.281
Expression system: Escherichia coli

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