2BG9

REFINED STRUCTURE OF THE NICOTINIC ACETYLCHOLINE RECEPTOR AT 4A RESOLUTION.


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Aggregation State: HELICAL ARRAY 
  • Reconstruction Method: HELICAL 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Refined Structure of the Nicotinic Acetylcholine Receptor at 4A Resolution

Unwin, N.

(2005) J.Mol.Biol. 346: 967

  • DOI: 10.1016/j.jmb.2004.12.031

  • PubMed Abstract: 
  • We present a refined model of the membrane-associated Torpedo acetylcholine (ACh) receptor at 4A resolution. An improved experimental density map was obtained from 342 electron images of helical tubes, and the refined structure was derived to an R-fa ...

    We present a refined model of the membrane-associated Torpedo acetylcholine (ACh) receptor at 4A resolution. An improved experimental density map was obtained from 342 electron images of helical tubes, and the refined structure was derived to an R-factor of 36.7% (R(free) 37.9%) by standard crystallographic methods, after placing the densities corresponding to a single molecule into an artificial unit cell. The agreement between experimental and calculated phases along the helical layer-lines was used to monitor progress in the refinement and to give an independent measure of the accuracy. The atomic model allowed a detailed description of the whole receptor in the closed-channel form, including the ligand-binding and intracellular domains, which have not previously been interpreted at a chemical level. We confirm that the two ligand-binding alpha subunits have a different extended conformation from the three other subunits in the closed channel, and identify several interactions on both pairs of subunit interfaces, and within the alpha subunits, which may be responsible for their "distorted" structures. The ACh-coordinating amino acid side-chains of the alpha subunits are far apart in the closed channel, indicating that a localised rearrangement, involving closure of loops B and C around the bound ACh molecule, occurs upon activation. A comparison of the structure of the alpha subunit with that of AChBP having ligand present, suggests how the localised rearrangement overcomes the distortions and initiates the rotational movements associated with opening of the channel. Both vestibules of the channel are strongly electronegative, providing a cation-stabilising environment at either entrance of the membrane pore. Access to the pore on the intracellular side is further influenced by narrow lateral windows, which would be expected to screen out electrostatically ions of the wrong charge and size.


    Related Citations: 
    • Structure and Gating Mechanism of the Acetylcholine Receptor Pore
      Miyazawa, A.,Fujiyoshi, Y.,Unwin, N.
      (2003) Nature 423: 949


    Organizational Affiliation

    MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK. mas@mrc-lmb.cam.ac.uk




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ACETYLCHOLINE RECEPTOR PROTEIN, ALPHA CHAIN
A, D
370Torpedo marmorataGene Names: CHRNA1
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Cys-Loop Receptor Family
Protein: 
Nicotinic Acetylcholine Receptor Pore (closed state)
Find proteins for P02711 (Torpedo marmorata)
Go to Gene View: CHRNA1
Go to UniProtKB:  P02711
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
ACETYLCHOLINE RECEPTOR PROTEIN, BETA CHAIN
B
370Torpedo marmorata
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Cys-Loop Receptor Family
Protein: 
Nicotinic Acetylcholine Receptor Pore (closed state)
Find proteins for Q6S3I0 (Torpedo marmorata)
Go to UniProtKB:  Q6S3I0
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
ACETYLCHOLINE RECEPTOR PROTEIN, DELTA CHAIN
C
369Torpedo marmorata
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Cys-Loop Receptor Family
Protein: 
Nicotinic Acetylcholine Receptor Pore (closed state)
Find proteins for Q6S3H8 (Torpedo marmorata)
Go to UniProtKB:  Q6S3H8
Entity ID: 4
MoleculeChainsSequence LengthOrganismDetails
ACETYLCHOLINE RECEPTOR PROTEIN, GAMMA CHAIN
E
370Torpedo marmorata
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Cys-Loop Receptor Family
Protein: 
Nicotinic Acetylcholine Receptor Pore (closed state)
Find proteins for Q6S3H9 (Torpedo marmorata)
Go to UniProtKB:  Q6S3H9
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Aggregation State: HELICAL ARRAY 
  • Reconstruction Method: HELICAL 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2004-12-17 
  • Released Date: 2005-02-16 
  • Deposition Author(s): Unwin, N.

Revision History 

  • Version 1.0: 2005-02-16
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance