Biological Assembly 1  

 3D View: Structure | Electron Density

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Hetero 3-mer - A1B1C1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 70.72 kDa 
• Atom Count: 4977 
• Residue Count: 644 
• Unique protein chains: 3

1ADQ

CRYSTAL STRUCTURE OF A HUMAN IGM RHEUMATOID FACTOR FAB IN COMPLEX WITH ITS AUTOANTIGEN IGG FC

• DOI: 10.2210/pdb1ADQ/pdb

• Classification: COMPLEX (IMMUNOGLOBULIN/AUTOANTIGEN)
• Organism(s): Homo sapiens
• Mutation(s): No 


• Deposited: 1997-02-18 Released: 1998-09-16 
• Deposition Author(s): Corper, A.L., Taussig, M.J., Sutton, B.J.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 3.15 Å
• R-Value Free: 0.289 
• R-Value Work: 0.225 
• R-Value Observed: 0.225 

Literature

Structure of human IgM rheumatoid factor Fab bound to its autoantigen IgG Fc reveals a novel topology of antibody-antigen interaction.

Corper, A.L., Sohi, M.K., Bonagura, V.R., Steinitz, M., Jefferis, R., Feinstein, A., Beale, D., Taussig, M.J., Sutton, B.J.

(1997) Nat Struct Biol 4: 374-381

• PubMed: 9145108 
• DOI: 10.1038/nsb0597-374
• Primary Citation of Related Structures:  
  1ADQ


• PubMed Abstract: 
  

Rheumatoid factors are the characteristic autoantibodies of rheumatoid arthritis, which bind to the Fc regions of IgG molecules. Here we report the crystal structure of the Fab fragment of a patient-derived IgM rheumatoid factor (RF-AN) complexed with human IgG4 Fc, at 3.2 A resolution. This is the first structure of an autoantibody-autoantigen complex. The epitope recognised in IgG Fc includes the C gamma 2/C gamma 3 cleft region, and overlaps the binding sites of bacterial Fc-binding proteins. The antibody residues involved in autorecognition are all located at the edge of the conventional combining site surface, leaving much of the latter available, potentially, for recognition of a different antigen. Since an important contact residue is somatic mutation, the structure implicates antigen-driven selection, following somatic mutation of germline genes, in the production of pathogenic rheumatoid factors.

---

Related Citations: 

• Crystallization of a Complex between the Fab Fragment of a Human Immunoglobulin M (Igm) Rheumatoid Factor (Rf-an) and the Fc Fragment of Human Igg4
  Sohi, M.K., Corper, A.L., Wan, T., Steinitz, M., Jefferis, R., Beale, D., He, M., Feinstein, A., Sutton, B.J., Taussig, M.J.
  (1996) Immunology 88: 636

---

Organizational Affiliation: 

Randall Institute, King's College London, UK.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
IGG4 REA FC	A	206	Homo sapiens	Mutation(s): 0  Gene Names: IGHG4
Find proteins for P01861 (Homo sapiens) Explore P01861  Go to UniProtKB:  P01861
NIH Common Fund Data Resources
PHAROS:  P01861 GTEx:  ENSG00000211892

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
IGM-LAMBDA RF-AN FAB (LIGHT CHAIN)	L	213	Homo sapiens	Mutation(s): 0

Entity ID: 3
Molecule	Chains	Sequence Length	Organism	Details	Image
IGM-LAMBDA RF-AN FAB (HEAVY CHAIN)	H	225	Homo sapiens	Mutation(s): 0

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 3.15 Å
• R-Value Free: 0.289 
• R-Value Work: 0.225 
• R-Value Observed: 0.225 
• Space Group: C 1 2 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 160.35	α = 90
b = 81.95	β = 98.27
c = 64.24	γ = 90

Software Package:

Software Name	Purpose
DENZO	data reduction
CCP4	data reduction
AMoRE	phasing
X-PLOR	refinement
CCP4	data scaling

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1997-02-18 
• Released Date: 1998-09-16 
Deposition Author(s): Corper, A.L., Taussig, M.J., Sutton, B.J.

Revision History 

• Version 1.0: 1998-09-16
  Type: Initial release
  
• Version 1.1: 2008-03-24
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance