2ITC

Potassium Channel KcsA-Fab complex in Sodium Chloride


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.2 Å
  • R-Value Free: 0.265 
  • R-Value Work: 0.246 

wwPDB Validation 3D Report Full Report


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:  2ITD, 2NLJ

  • 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: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Antibody Fab fragment heavy chain
A
219N/AN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Antibody Fab fragment light chain
B
212N/AN/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Voltage-gated potassium channel
C
124Streptomyces lividansGene Names: kcsA (skc1)
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Channels: Potassium, Sodium, & Proton Ion-Selective
Protein: 
KcsA Potassium channel, H+ gated
Find proteins for P0A334 (Streptomyces lividans)
Go to UniProtKB:  P0A334
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
C
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.2 Å
  • R-Value Free: 0.265 
  • R-Value Work: 0.246 
  • Space Group: I 4
Unit Cell:
Length (Å)Angle (°)
a = 155.501α = 90.00
b = 155.501β = 90.00
c = 75.820γ = 90.00
Software Package:
Software NamePurpose
CBASSdata collection
MOLREPphasing
DENZOdata reduction
CNSrefinement
SCALEPACKdata scaling
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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