4J9Z

Calcium-calmodulin complexed with the calmodulin binding domain from a small conductance potassium channel splice variant and NS309


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.66 Å
  • R-Value Free: 0.221 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Unstructured to structured transition of an intrinsically disordered protein peptide in coupling Ca2+-sensing and SK channel activation.

Zhang, M.Pascal, J.M.Zhang, J.F.

(2013) Proc Natl Acad Sci U S A 110: 4828-4833

  • DOI: 10.1073/pnas.1220253110
  • Primary Citation of Related Structures:  
    4J9Y, 4J9Z

  • PubMed Abstract: 
  • Most proteins, such as ion channels, form well-organized 3D structures to carry out their specific functions. A typical voltage-gated potassium channel subunit has six transmembrane segments (S1-S6) to form the voltage-sensing domain and the pore domain. ...

    Most proteins, such as ion channels, form well-organized 3D structures to carry out their specific functions. A typical voltage-gated potassium channel subunit has six transmembrane segments (S1-S6) to form the voltage-sensing domain and the pore domain. Conformational changes of these domains result in opening of the channel pore. Intrinsically disordered (ID) proteins/peptides are considered equally important for the protein functions. However, it is difficult to explore the structural features underlying the functions of ID proteins/peptides by conventional methods, such as X-ray crystallography, because of the flexibility of their secondary structures. Unlike voltage-gated potassium channels, families of small- and intermediate-conductance Ca(2+)-activated potassium (SK/IK) channels with important roles in regulating membrane excitability are activated exclusively by Ca(2+)-bound calmodulin (CaM). Upon binding of Ca(2+) to CaM, a 2 × 2 structure forms between CaM and the CaM-binding domain. A channel fragment that connects S6 and the CaM-binding domain is not visible in the protein crystal structure, suggesting that this fragment is an ID fragment. Here we show that the conformation of the ID fragment in SK channels becomes readily identifiable in the presence of NS309, the most potent compound that potentiates the channel activities. This well-defined conformation of the ID fragment, stabilized by NS309, increases the channel open probability at a given Ca(2+) concentration. Our results demonstrate that the ID fragment, itself a target for drugs modulating SK channel activities, plays a unique role in coupling Ca(2+) sensing by CaM and mechanical opening of SK channels.


    Organizational Affiliation

    Department of Molecular Physiology and Biophysics, Thomas Jefferson University, Philadelphia, PA 19107, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Small conductance calcium-activated potassium channel protein 2 B102Rattus norvegicusMutation(s): 0 
Gene Names: Kcnn2
Find proteins for P70604 (Rattus norvegicus)
Explore P70604 
Go to UniProtKB:  P70604
Protein Feature View
Expand
  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Calmodulin R149Rattus norvegicusMutation(s): 0 
Gene Names: 
Calm1CalmCamCam1Calm2Cam2CambCalm3Cam3Camc...
Calm1CalmCamCam1Calm2Cam2CambCalm3Cam3CamcCaMI

Find proteins for P0DP29 (Rattus norvegicus)
Explore P0DP29 
Go to UniProtKB:  P0DP29
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.66 Å
  • R-Value Free: 0.221 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.192 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 77.2α = 90
b = 66.85β = 93.81
c = 64.83γ = 90
Software Package:
Software NamePurpose
SCALAdata scaling
PHENIXrefinement
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-03-27
    Type: Initial release
  • Version 1.1: 2013-04-03
    Changes: Database references