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 1.4 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: https://doi.org/10.1016/j.jmb.2004.12.031
  • Primary Citation of Related Structures:  
    2BG9

  • 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-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.


  • Organizational Affiliation

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


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ACETYLCHOLINE RECEPTOR PROTEIN, ALPHA CHAIN
A, D
370Torpedo marmorataMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for P02711 (Torpedo marmorata)
Explore P02711 
Go to UniProtKB:  P02711
Entity Groups  
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UniProt GroupP02711
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  • Reference Sequence
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Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
ACETYLCHOLINE RECEPTOR PROTEIN, BETA CHAIN370Torpedo marmorataMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for Q6S3I0 (Torpedo marmorata)
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Go to UniProtKB:  Q6S3I0
Entity Groups  
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UniProt GroupQ6S3I0
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Entity ID: 3
MoleculeChains Sequence LengthOrganismDetailsImage
ACETYLCHOLINE RECEPTOR PROTEIN, DELTA CHAIN369Torpedo marmorataMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for Q6S3H8 (Torpedo marmorata)
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Go to UniProtKB:  Q6S3H8
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UniProt GroupQ6S3H8
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  • Reference Sequence
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Entity ID: 4
MoleculeChains Sequence LengthOrganismDetailsImage
ACETYLCHOLINE RECEPTOR PROTEIN, GAMMA CHAIN370Torpedo marmorataMutation(s): 0 
Membrane Entity: Yes 
UniProt
Find proteins for Q6S3H9 (Torpedo marmorata)
Explore Q6S3H9 
Go to UniProtKB:  Q6S3H9
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UniProt GroupQ6S3H9
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

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

Structure Validation

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Entry History 

Deposition Data

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

Revision History  (Full details and data files)

  • Version 1.0: 2005-02-16
    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: 2019-10-02
    Changes: Author supporting evidence, Data collection, Other
  • Version 1.4: 2019-10-23
    Changes: Data collection, Other