4XAM

Complement component C4b


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.20 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.217 
  • R-Value Observed: 0.219 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Structural Basis for the Function of Complement Component C4 within the Classical and Lectin Pathways of Complement.

Mortensen, S.Kidmose, R.T.Petersen, S.V.Szilagyi, A.Prohaszka, Z.Andersen, G.R.

(2015) J Immunol 194: 5488-5496

  • DOI: 10.4049/jimmunol.1500087
  • Structures With Same Primary Citation

  • PubMed Abstract: 
  • Complement component C4 is a central protein in the classical and lectin pathways within the complement system. During activation of complement, its major fragment C4b becomes covalently attached to the surface of pathogens and altered self-tissue, w ...

    Complement component C4 is a central protein in the classical and lectin pathways within the complement system. During activation of complement, its major fragment C4b becomes covalently attached to the surface of pathogens and altered self-tissue, where it acts as an opsonin marking the surface for removal. Moreover, C4b provides a platform for assembly of the proteolytically active convertases that mediate downstream complement activation by cleavage of C3 and C5. In this article, we present the crystal and solution structures of the 195-kDa C4b. Our results provide the molecular details of the rearrangement accompanying C4 cleavage and suggest intramolecular flexibility of C4b. The conformations of C4b and its paralogue C3b are shown to be remarkably conserved, suggesting that the convertases from the classical and alternative pathways are likely to share their overall architecture and mode of substrate recognition. We propose an overall molecular model for the classical pathway C5 convertase in complex with C5, suggesting that C3b increases the affinity for the substrate by inducing conformational changes in C4b rather than a direct interaction with C5. C4b-specific features revealed by our structural studies are probably involved in the assembly of the classical pathway C3/C5 convertases and C4b binding to regulators.


    Organizational Affiliation

    Department of Molecular Biology and Genetics, Aarhus University, DK-8000 Aarhus, Denmark; gra@mbg.au.dk.



Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Complement C4-B
A, B
656Homo sapiensMutation(s): 0 
Gene Names: C4BCO4CPAMD3C4B_2
Find proteins for P0C0L5 (Homo sapiens)
Go to UniProtKB:  P0C0L5
NIH Common Fund Data Resources
PHAROS  P0C0L5
Protein Feature View
  • Reference Sequence

Find similar proteins by: Sequence  |  Structure

Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Complement C4-A
C, E
690Homo sapiensMutation(s): 0 
Gene Names: C4ACO4CPAMD2
Find proteins for P0C0L4 (Homo sapiens)
Go to UniProtKB:  P0C0L4
NIH Common Fund Data Resources
PHAROS  P0C0L4
Protein Feature View
  • Reference Sequence

Find similar proteins by: Sequence  |  Structure

Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Complement C4-A
D, F
291Homo sapiensMutation(s): 0 
Gene Names: C4ACO4CPAMD2
Find proteins for P0C0L4 (Homo sapiens)
Go to UniProtKB:  P0C0L4
NIH Common Fund Data Resources
PHAROS  P0C0L4
Protein Feature View
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 4.20 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.217 
  • R-Value Observed: 0.219 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 121.5α = 90
b = 161.08β = 107.26
c = 131.6γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
XDSdata reduction
XSCALEdata scaling
Omodel building
PHASERphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2015-05-06
    Type: Initial release
  • Version 1.1: 2015-05-27
    Changes: Database references