2ICF

CRIg bound to C3b


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.1 Å
  • R-Value Free: 0.330 
  • R-Value Work: 0.252 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structure of C3b in complex with CRIg gives insights into regulation of complement activation.

Wiesmann, C.Katschke, K.J.Yin, J.Helmy, K.Y.Steffek, M.Fairbrother, W.J.McCallum, S.A.Embuscado, L.DeForge, L.Hass, P.E.van Lookeren Campagne, M.

(2006) Nature 444: 217-220

  • DOI: 10.1038/nature05263
  • Primary Citation of Related Structures:  2ICC, 2ICE

  • PubMed Abstract: 
  • The complement system is a key part of the innate immune system, and is required for clearance of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitmen ...

    The complement system is a key part of the innate immune system, and is required for clearance of pathogens from the bloodstream. After exposure to pathogens, the third component of the complement system, C3, is cleaved to C3b which, after recruitment of factor B, initiates formation of the alternative pathway convertases. CRIg, a complement receptor expressed on macrophages, binds to C3b and iC3b mediating phagocytosis of the particles, but it is unknown how CRIg selectively recognizes proteolytic C3-fragments and whether binding of CRIg to C3b inhibits convertase activation. Here we present the crystal structure of C3b in complex with CRIg and, using CRIg mutants, provide evidence that CRIg acts as an inhibitor of the alternative pathway of complement. The structure shows that activation of C3 induces major structural rearrangements, including a dramatic movement (>80 A) of the thioester-bond-containing domain through which C3b attaches to pathogen surfaces. We show that CRIg is not only a phagocytic receptor, but also a potent inhibitor of the alternative pathway convertases. The structure provides insights into the complex macromolecular structural rearrangements that occur during complement activation and inhibition. Moreover, our structure-function studies relating the structural basis of complement activation and the means by which CRIg inhibits the convertases provide important clues to the development of therapeutics that target complement.


    Organizational Affiliation

    Department of Protein Engineering, 1 DNA Way, South San Francisco, California 94080, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Complement C3 beta chain
A
642Homo sapiensGene Names: C3 (CPAMD1)
Find proteins for P01024 (Homo sapiens)
Go to Gene View: C3
Go to UniProtKB:  P01024
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Complement C3 alpha chain
B
915Homo sapiensGene Names: C3 (CPAMD1)
Find proteins for P01024 (Homo sapiens)
Go to Gene View: C3
Go to UniProtKB:  P01024
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
V-set and immunoglobulin domain-containing protein 4
S
119Homo sapiensGene Names: VSIG4 (CRIg, Z39IG)
Find proteins for Q9Y279 (Homo sapiens)
Go to Gene View: VSIG4
Go to UniProtKB:  Q9Y279
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
BMA
Query on BMA

Download SDF File 
Download CCD File 
A
BETA-D-MANNOSE
C6 H12 O6
WQZGKKKJIJFFOK-RWOPYEJCSA-N
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
A, B
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.1 Å
  • R-Value Free: 0.330 
  • R-Value Work: 0.252 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 97.614α = 90.00
b = 255.749β = 90.00
c = 180.302γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2006-09-12 
  • Released Date: 2006-11-07 
  • Deposition Author(s): Wiesmann, C.

Revision History 

  • Version 1.0: 2006-11-07
    Type: Initial release
  • Version 1.1: 2008-02-06
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Refinement description, Version format compliance
  • Version 1.3: 2013-09-18
    Type: Derived calculations