Crystal Structure of the Human C3a desArg anaphylatoxin

Experimental Data Snapshot

  • Resolution: 2.60 Å
  • R-Value Free: 0.270 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.227 

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Human C3a and C3a desArg anaphylatoxins have conserved structures, in contrast to C5a and C5a desArg.

Bajic, G.Yatime, L.Klos, A.Andersen, G.R.

(2013) Protein Sci 22: 204-212

  • DOI: https://doi.org/10.1002/pro.2200
  • Primary Citation of Related Structures:  
    4HW5, 4HWJ

  • PubMed Abstract: 

    Complement is a part of innate immunity that has a critical role in the protection against microbial infections, bridges the innate with the adaptive immunity and initiates inflammation. Activation of the complement, by specific recognition of molecular patterns presented by an activator, for example, a pathogen cell, in the classical and lectin pathways or spontaneously in the alternative pathway, leads to the opsonization of the activator and the production of pro-inflammatory molecules such as the C3a anaphylatoxin. The biological function of this anaphylatoxin is regulated by carboxypeptidase B, a plasma protease that cleaves off the C-terminal arginine yielding C3a desArg, an inactive form. While functional assays demonstrate strikingly different physiological effects between C3a and C3a desArg, no structural information is available on the possible conformational differences between the two proteins. Here, we report a novel and simple expression and purification protocol for recombinant human C3a and C3a desArg anaphylatoxins, as well as their crystal structures at 2.3 and 2.6 Å, respectively. Structural analysis revealed no significant conformational differences between the two anaphylatoxins in contrast to what has been reported for C5a and C5a desArg. We compare the structures of different anaphylatoxins and discuss the relevance of their observed conformations to complement activation and binding of the anaphylatoxins to their cognate receptors.

  • Organizational Affiliation

    Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Complement C382Homo sapiensMutation(s): 0 
Gene Names: C3CPAMD1
UniProt & NIH Common Fund Data Resources
Find proteins for P01024 (Homo sapiens)
Explore P01024 
Go to UniProtKB:  P01024
PHAROS:  P01024
GTEx:  ENSG00000125730 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01024
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on SO4

Download Ideal Coordinates CCD File 
O4 S
Experimental Data & Validation

Experimental Data

  • Resolution: 2.60 Å
  • R-Value Free: 0.270 
  • R-Value Work: 0.223 
  • R-Value Observed: 0.227 
  • Space Group: P 63 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 63.75α = 90
b = 63.75β = 90
c = 106.43γ = 120
Software Package:
Software NamePurpose
XSCALEdata scaling
PDB_EXTRACTdata extraction
MxCuBEdata collection

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-12-12
    Type: Initial release
  • Version 1.1: 2013-02-13
    Changes: Database references
  • Version 1.2: 2018-03-07
    Changes: Data collection