Crystal structure of apoCalmodulin

Experimental Data Snapshot

  • Resolution: 2.54 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.227 
  • R-Value Observed: 0.227 

wwPDB Validation   3D Report Full Report

This is version 1.3 of the entry. See complete history


Crystal structures of apocalmodulin and an apocalmodulin/SK potassium channel gating domain complex.

Schumacher, M.A.Crum, M.Miller, M.C.

(2004) Structure 12: 849-860

  • DOI: https://doi.org/10.1016/j.str.2004.03.017
  • Primary Citation of Related Structures:  
    1QX5, 1QX7

  • PubMed Abstract: 

    Small conductance Ca2+-activated K+ channels (SK channels) are composed of the pore-forming alpha subunit and calmodulin (CaM). CaM binds to a region of the alpha subunit called the CaM binding domain (CaMBD), located intracellular and immediately C-terminal to the inner helix gate, in either the presence or absence of Ca2+. SK gating occurs when Ca2+ binds the N lobe of CaM thereby transmitting the signal to the attached inner helix gate to open. Here we present crystal structures of apoCaM and apoCaM/SK2 CaMBD complex. Several apoCaM crystal forms with multiple (12) packing environments reveal the same EF hand domain-swapped dimer providing potentially new insight into CaM regulation. The apoCaM/SK2 CaMBD structure, combined with our Ca2+/CaM/CaMBD structure suggests that Ca2+ binding induces folding and dimerization of the CaMBD, which causes large CaMBD-CaM C lobe conformational changes, including a >90 degrees rotation of the region of the CaMBD directly connected to the gate.

  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR 97239 USA. schumacm@ohsu.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Calmodulin148Rattus norvegicusMutation(s): 0 
Find proteins for P0DP29 (Rattus norvegicus)
Explore P0DP29 
Go to UniProtKB:  P0DP29
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0DP29
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.54 Å
  • R-Value Free: 0.277 
  • R-Value Work: 0.227 
  • R-Value Observed: 0.227 
  • Space Group: P 31
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 146α = 90
b = 146β = 90
c = 78γ = 120
Software Package:
Software NamePurpose
MOSFLMdata reduction
CCP4data scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-08-31
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references