Calcium release-activated calcium (CRAC) channel ORAI

Experimental Data Snapshot

  • Resolution: 3.35 Å
  • R-Value Free: 0.279 
  • R-Value Work: 0.278 
  • R-Value Observed: 0.278 

wwPDB Validation   3D Report Full Report

This is version 1.3 of the entry. See complete history


Crystal structure of the calcium release-activated calcium channel Orai.

Hou, X.Pedi, L.Diver, M.M.Long, S.B.

(2012) Science 338: 1308-1313

  • DOI: https://doi.org/10.1126/science.1228757
  • Primary Citation of Related Structures:  
    4HKR, 4HKS

  • PubMed Abstract: 

    The plasma membrane protein Orai forms the pore of the calcium release-activated calcium (CRAC) channel and generates sustained cytosolic calcium signals when triggered by depletion of calcium from the endoplasmic reticulum. The crystal structure of Orai from Drosophila melanogaster, determined at 3.35 angstrom resolution, reveals that the calcium channel is composed of a hexameric assembly of Orai subunits arranged around a central ion pore. The pore traverses the membrane and extends into the cytosol. A ring of glutamate residues on its extracellular side forms the selectivity filter. A basic region near the intracellular side can bind anions that may stabilize the closed state. The architecture of the channel differs markedly from other ion channels and gives insight into the principles of selective calcium permeation and gating.

  • Organizational Affiliation

    Structural Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Calcium release-activated calcium channel protein 1
A, B
214Drosophila melanogasterMutation(s): 4 
Gene Names: olf186-FCRACM1olf186CG11430
Membrane Entity: Yes 
Find proteins for Q9U6B8 (Drosophila melanogaster)
Explore Q9U6B8 
Go to UniProtKB:  Q9U6B8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9U6B8
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.35 Å
  • R-Value Free: 0.279 
  • R-Value Work: 0.278 
  • R-Value Observed: 0.278 
  • Space Group: P 21 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 117.91α = 90
b = 117.91β = 90
c = 117.91γ = 90
Software Package:
Software NamePurpose
CBASSdata collection
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-11-28
    Type: Initial release
  • Version 1.1: 2012-12-12
    Changes: Database references
  • Version 1.2: 2012-12-26
    Changes: Database references
  • Version 1.3: 2023-09-20
    Changes: Data collection, Database references, Derived calculations, Refinement description