Structure of a K+ selective NaK mutant

Experimental Data Snapshot

  • Resolution: 1.55 Å
  • R-Value Free: 0.215 
  • R-Value Work: 0.200 

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This is version 1.3 of the entry. See complete history


Tuning the ion selectivity of tetrameric cation channels by changing the number of ion binding sites.

Derebe, M.G.Sauer, D.B.Zeng, W.Alam, A.Shi, N.Jiang, Y.

(2011) Proc Natl Acad Sci U S A 108: 598-602

  • DOI: https://doi.org/10.1073/pnas.1013636108
  • Primary Citation of Related Structures:  
    3K03, 3OUF, 3OUS

  • PubMed Abstract: 

    Selective ion conduction across ion channel pores is central to cellular physiology. To understand the underlying principles of ion selectivity in tetrameric cation channels, we engineered a set of cation channel pores based on the nonselective NaK channel and determined their structures to high resolution. These structures showcase an ensemble of selectivity filters with a various number of contiguous ion binding sites ranging from 2 to 4, with each individual site maintaining a geometry and ligand environment virtually identical to that of equivalent sites in K(+) channel selectivity filters. Combined with single channel electrophysiology, we show that only the channel with four ion binding sites is K(+) selective, whereas those with two or three are nonselective and permeate Na(+) and K(+) equally well. These observations strongly suggest that the number of contiguous ion binding sites in a single file is the key determinant of the channel's selectivity properties and the presence of four sites in K(+) channels is essential for highly selective and efficient permeation of K(+) ions.

  • Organizational Affiliation

    Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9040, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Potassium channel protein
A, B
97Bacillus cereus m1550Mutation(s): 1 
Gene Names: bcere0011_5790
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on MPD

Download Ideal Coordinates CCD File 
C [auth A],
D [auth A],
J [auth B],
K [auth B],
L [auth B]
C6 H14 O2
Query on K

Download Ideal Coordinates CCD File 
E [auth A]
F [auth A]
G [auth A]
H [auth A]
I [auth A]
E [auth A],
F [auth A],
G [auth A],
H [auth A],
I [auth A],
M [auth B],
N [auth B],
O [auth B],
P [auth B]
Experimental Data & Validation

Experimental Data

  • Resolution: 1.55 Å
  • R-Value Free: 0.215 
  • R-Value Work: 0.200 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.939α = 90
b = 67.939β = 90
c = 89.638γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data collection

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2011-01-12
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-11-08
    Changes: Refinement description
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references, Derived calculations