Cryo-EM structures of undocked innexin-6 hemichannels in phospholipids

Sci Adv. 2020 Feb 12;6(7):eaax3157. doi: 10.1126/sciadv.aax3157. eCollection 2020 Feb.


Gap junctions form intercellular conduits with a large pore size whose closed and open states regulate communication between adjacent cells. The structural basis of the mechanism by which gap junctions close, however, remains uncertain. Here, we show the cryo-electron microscopy structures of Caenorhabditis elegans innexin-6 (INX-6) gap junction proteins in an undocked hemichannel form. In the nanodisc-reconstituted structure of the wild-type INX-6 hemichannel, flat double-layer densities obstruct the channel pore. Comparison of the hemichannel structures of a wild-type INX-6 in detergent and nanodisc-reconstituted amino-terminal deletion mutant reveals that lipid-mediated amino-terminal rearrangement and pore obstruction occur upon nanodisc reconstitution. Together with molecular dynamics simulations and electrophysiology functional assays, our results provide insight into the closure of the INX-6 hemichannel in a lipid bilayer before docking of two hemichannels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins / chemistry
  • Caenorhabditis elegans Proteins / ultrastructure*
  • Connexins / chemistry
  • Connexins / ultrastructure*
  • Cryoelectron Microscopy*
  • Lipid Bilayers / chemistry
  • Molecular Docking Simulation*
  • Molecular Dynamics Simulation
  • Nanoparticles / chemistry
  • Oocytes / metabolism
  • Phospholipids / chemistry*
  • Xenopus / metabolism


  • Caenorhabditis elegans Proteins
  • Connexins
  • Lipid Bilayers
  • Phospholipids
  • inx-6 protein, C elegans