C-alpha model fitted into the EM structure of Cx26M34A

Experimental Data Snapshot


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Asymmetric configurations and N-terminal rearrangements in connexin26 gap junction channels.

Oshima, A.Tani, K.Toloue, M.M.Hiroaki, Y.Smock, A.Inukai, S.Cone, A.Nicholson, B.J.Sosinsky, G.E.Fujiyoshi, Y.

(2011) J Mol Biol 405: 724-735

  • DOI: https://doi.org/10.1016/j.jmb.2010.10.032
  • Primary Citation of Related Structures:  
    3IZ1, 3IZ2

  • PubMed Abstract: 

    Gap junction channels are unique in that they possess multiple mechanisms for channel closure, several of which involve the N terminus as a key component in gating, and possibly assembly. Here, we present electron crystallographic structures of a mutant human connexin26 (Cx26M34A) and an N-terminal deletion of this mutant (Cx26M34Adel2-7) at 6-Å and 10-Å resolutions, respectively. The three-dimensional map of Cx26M34A was improved by data from 60° tilt images and revealed a breakdown of the hexagonal symmetry in a connexin hemichannel, particularly in the cytoplasmic domain regions at the ends of the transmembrane helices. The Cx26M34A structure contained an asymmetric density in the channel vestibule ("plug") that was decreased in the Cx26M34Adel2-7 structure, indicating that the N terminus significantly contributes to form this plug feature. Functional analysis of the Cx26M34A channels revealed that these channels are predominantly closed, with the residual electrical conductance showing normal voltage gating. N-terminal deletion mutants with and without the M34A mutation showed no electrical activity in paired Xenopus oocytes and significantly decreased dye permeability in HeLa cells. Comparing this closed structure with the recently published X-ray structure of wild-type Cx26, which is proposed to be in an open state, revealed a radial outward shift in the transmembrane helices in the closed state, presumably to accommodate the N-terminal plug occluding the pore. Because both Cx26del2-7 and Cx26M34Adel2-7 channels are closed, the N terminus appears to have a prominent role in stabilizing the open configuration.

  • Organizational Affiliation

    Department of Biophysics, Faculty of Science, Kyoto University, Oiwake, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Gap junction beta-2 protein
A, B, C
238Homo sapiensMutation(s): 0 
Gene Names: GJB2
Membrane Entity: Yes 
UniProt & NIH Common Fund Data Resources
Find proteins for P29033 (Homo sapiens)
Explore P29033 
Go to UniProtKB:  P29033
PHAROS:  P29033
GTEx:  ENSG00000165474 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP29033
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 112.4α = 90
b = 111.2β = 90
c = 300γ = 90
EM Software:
TaskSoftware PackageVersion

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-11-03
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2018-07-18
    Changes: Author supporting evidence, Data collection
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references, Refinement description