Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report | Ligand Interaction | Predict Membrane 

Global Symmetry: Cyclic - C4  (3D View)
Global Stoichiometry: Hetero 12-mer - A4B4C4 

Biological assembly 1 assigned by authors and generated by PQS (software)

Macromolecule Content

• Total Structure Weight: 60.56 kDa 
• Atom Count: 4166 
• Modelled Residue Count: 534 
• Deposited Residue Count: 555 
• Unique protein chains: 3

2BOB

Potassium channel KcsA-Fab complex in thallium with tetrabutylammonium (TBA)

• PDB DOI: 10.2210/pdb2BOB/pdb

• Classification: IMMUNE SYSTEM/TRANSPORT PROTEIN
• Organism(s): Mus musculus, Streptomyces lividans
• Expression System: Escherichia coli
• Mutation(s): Yes 
• Membrane Protein: Yes  PDBTMMemProtMDmpstruc


• Deposited: 2005-04-09 Released: 2005-04-27 
• Deposition Author(s): Lenaeus, M.J., Vamvouka, M., Focia, P.J., Gross, A.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 2.76 Å
• R-Value Free: 0.251 
• R-Value Work: 0.220 
• R-Value Observed: 0.222 

Literature

Structural Basis of Tea Blockade in a Model Potassium Channel

Lenaeus, M.J., Vamvouka, M., Focia, P.J., Gross, A.

(2005) Nat Struct Mol Biol 12: 454

• PubMed: 15852022 
• DOI: 10.1038/nsmb929
• Primary Citation of Related Structures:  
  2BOB, 2BOC


• PubMed Abstract: 
  

Potassium channels catalyze the selective transfer of potassium across the cell membrane and are essential for setting the resting potential in cells, controlling heart rate and modulating the firing pattern in neurons. Tetraethylammonium (TEA) blocks ion conduction through potassium channels in a voltage-dependent manner from both sides of the membrane. Here we show the structural basis of TEA blockade by cocrystallizing the prokaryotic potassium channel KcsA with two selective TEA analogs. TEA binding at both sites alters ion occupancy in the selectivity filter; these findings underlie the mutual destabilization and voltage-dependence of TEA blockade. We propose that TEA blocks potassium channels by acting as a potassium analog at the dehydration transition step during permeation.

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Organizational Affiliation: 

Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, Illinois 60611, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
ANTIBODY FAB FRAGMENT HEAVY CHAIN	A	219	Mus musculus	Mutation(s): 0

Entity ID: 2
Molecule	Chains	Sequence Length	Organism	Details	Image
ANTIBODY FAB FRAGMENT LIGHT CHAIN	B	212	Mus musculus	Mutation(s): 0

Entity ID: 3
Molecule	Chains	Sequence Length	Organism	Details	Image
POTASSIUM CHANNEL KCSA	C	124	Streptomyces lividans	Mutation(s): 1  Gene Names: kcsA, skc1 Membrane Entity: Yes
UniProt
Find proteins for P0A334 (Streptomyces lividans) Explore P0A334  Go to UniProtKB:  P0A334

Small Molecules

Ligands 3 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
TBA	F [auth C]	TETRABUTYLAMMONIUM ION C16 H36 N DZLFLBLQUQXARW-UHFFFAOYSA-N
TL	D [auth C]	THALLIUM (I) ION Tl ZLUSCZLCHQSJRU-UHFFFAOYSA-N
CO	E [auth C]	COBALT (II) ION Co XLJKHNWPARRRJB-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 2.76 Å
• R-Value Free: 0.251 
• R-Value Work: 0.220 
• R-Value Observed: 0.222 
• Space Group: I 4

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 155.267	α = 90
b = 155.267	β = 90
c = 75.555	γ = 90

Software Package:

Software Name	Purpose
REFMAC	refinement
XDS	data reduction
XDS	data scaling
CNS	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2005-04-09 
• Released Date: 2005-04-27 
Deposition Author(s): Lenaeus, M.J., Vamvouka, M., Focia, P.J., Gross, A.

Revision History  

• Version 1.0: 2005-04-27
  Type: Initial release
  
• Version 1.1: 2011-05-08
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2017-07-12
  Changes: Derived calculations