Gap junction channel structure in the early 21st century: facts and fantasies

Curr Opin Cell Biol. 2007 Oct;19(5):521-8. doi: 10.1016/j.ceb.2007.09.001. Epub 2007 Oct 22.

Abstract

Gap junction channels connect the cytoplasms of adjacent cells through the end-to-end docking of single-membrane structures called connexons, formed by a ring of six connexin monomers. Each monomer contains four transmembrane alpha-helices, for a total of 24 alpha-helices in a connexon. The fundamental structure of the connexon pore is probably similar in unpaired connexons and junctional channels, and for channels formed by different connexin isoforms. Nevertheless, variability in results from structurally focused mutagenesis and electrophysiological studies raise uncertainty about the specific assignments of the transmembrane helices. Mapping of human mutations onto a suggested C(alpha) model predicts that mutations that disrupt helix-helix packing impair channel function. An experimentally determined structure at atomic resolution will be essential to confirm and resolve these concepts.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Cell Communication / physiology
  • Connexins / genetics
  • Connexins / metabolism
  • Connexins / ultrastructure*
  • Cryoelectron Microscopy
  • Gap Junctions / metabolism
  • Gap Junctions / ultrastructure*
  • Humans
  • Models, Molecular
  • Mutation
  • Protein Structure, Quaternary*
  • Protein Structure, Secondary*
  • Protein Subunits / chemistry*
  • Protein Subunits / genetics
  • Protein Subunits / metabolism

Substances

  • Connexins
  • Protein Subunits