Crystal structure of the CLIC homologue EXC-4 from c. elegans

Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.235 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.190 

Starting Model: experimental
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Comparison of vertebrate and invertebrate CLIC proteins: The crystal structures of Caenorhabditis elegans EXC-4 and Drosophila melanogaster DmCLIC

Littler, D.R.Harrop, S.J.Brown, L.J.Pankhurst, G.J.Mynott, A.V.Luciani, P.Mandyam, R.A.Mazzanti, M.Tanda, S.Berryman, M.A.Breit, S.N.Curmi, P.M.G.

(2007) Proteins 71: 364-378

  • DOI: https://doi.org/10.1002/prot.21704
  • Primary Citation of Related Structures:  
    2YV7, 2YV9

  • PubMed Abstract: 

    The crystal structures of two CLIC family members DmCLIC and EXC-4 from the invertebrates Drosophila melanogaster and Caenorhabditis elegans, respectively, have been determined. The proteins adopt a glutathione S-transferase (GST) fold. The structures are highly homologous to each other and more closely related to the known structures of the human CLIC1 and CLIC4 than to GSTs. The invertebrate CLICs show several unique features including an elongated C-terminal extension and a divalent metal binding site. The latter appears to alter the ancestral glutathione binding site, and thus, the invertebrate CLICs are unlikely to bind glutathione in the same manner as the GST proteins. Purified recombinant DmCLIC and EXC-4 both bind to lipid bilayers and can form ion channels in artificial lipid bilayers, albeit at low pH. EXC-4 differs from other CLIC proteins in that the conserved redox-active cysteine at the N-terminus of helix 1 is replaced by an aspartic acid residue. Other key distinguishing features of EXC-4 include the fact that it binds to artificial bilayers at neutral pH and this binding is not sensitive to oxidation. These differences with other CLIC family members are likely to be due to the substitution of the conserved cysteine by aspartic acid.

  • Organizational Affiliation

    School of Physics, University of New South Wales, New South Wales 2052, Australia.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Chloride intracellular channel exc-4
A, B
291Caenorhabditis elegansMutation(s): 0 
Gene Names: exc-4
Find proteins for Q8WQA4 (Caenorhabditis elegans)
Explore Q8WQA4 
Go to UniProtKB:  Q8WQA4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8WQA4
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.235 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.190 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 54.913α = 90
b = 91.395β = 99.61
c = 63.286γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2008-02-19
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2023-10-25
    Changes: Data collection, Database references, Derived calculations, Refinement description