2ITD

Potassium Channel KcsA-Fab complex in Barium Chloride


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.241 

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This is version 1.4 of the entry. See complete history


Literature

Structural and Thermodynamic Properties of Selective Ion Binding in a K(+) Channel.

Lockless, S.W.Zhou, M.Mackinnon, R.

(2007) PLoS Biol 5: e121-e121

  • DOI: 10.1371/journal.pbio.0050121
  • Primary Citation of Related Structures:  
    2NLJ, 2ITD, 2ITC

  • PubMed Abstract: 
  • Thermodynamic measurements of ion binding to the Streptomyces lividans K(+) channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray ...

    Thermodynamic measurements of ion binding to the Streptomyces lividans K(+) channel were carried out using isothermal titration calorimetry, whereas atomic structures of ion-bound and ion-free conformations of the channel were characterized by x-ray crystallography. Here we use these assays to show that the ion radius dependence of selectivity stems from the channel's recognition of ion size (i.e., volume) rather than charge density. Ion size recognition is a function of the channel's ability to adopt a very specific conductive structure with larger ions (K(+), Rb(+), Cs(+), and Ba(2+)) bound and not with smaller ions (Na(+), Mg(2+), and Ca(2+)). The formation of the conductive structure involves selectivity filter atoms that are in direct contact with bound ions as well as protein atoms surrounding the selectivity filter up to a distance of 15 A from the ions. We conclude that ion selectivity in a K(+) channel is a property of size-matched ion binding sites created by the protein structure.


    Organizational Affiliation

    Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, New York, New York, United States of America.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
antibody Fab fragment heavy chainA219Mus musculusMutation(s): 0 
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
antibody Fab fragment light chainB212Mus musculusMutation(s): 0 
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetailsImage
Voltage-gated potassium channelC124Streptomyces lividansMutation(s): 1 
Gene Names: kcsAskc1
Membrane protein
Mpstruc
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Channels: Potassium, Sodium, & Proton Ion-Selective
Protein: 
KcsA-Fab complex in NaCl
Find proteins for P0A334 (Streptomyces lividans)
Explore P0A334 
Go to UniProtKB:  P0A334
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
BA
Query on BA

Download CCD File 
C
BARIUM ION
Ba
XDFCIPNJCBUZJN-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.241 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 156.075α = 90
b = 156.075β = 90
c = 75.424γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
MOLREPphasing
CNSrefinement
PDB_EXTRACTdata extraction
CBASSdata collection

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-05-15
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2011-11-16
    Changes: Atomic model
  • Version 1.4: 2017-10-18
    Changes: Refinement description