Antoine Taly - A prokaryotic proton-gated ion channel from the nicotinic acetylcholine receptor family.

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  Publication Details (including relevant citation   information):

  Nature. 2007 Jan 4;445(7123):116-9.


  Ligand-gated ion channels (LGICs) mediate excitatory and   inhibitory transmission in the nervous system. Among them, the   pentameric or 'Cys-loop' receptors (pLGICs) compose a family that   until recently was found in only eukaryotes. Yet a recent genome   search identified putative homologues of these proteins in   several bacterial species. Here we report the cloning, expression   and functional identification of one of these putative homologues   from the cyanobacterium Gloeobacter violaceus. It was expressed   as a ****-oligomer in HEK 293 cells and Xenopus oocytes,   generating a transmembrane cationic channel that is opened by   extracellular protons and shows slow kinetics of activation, no   desensitization and a single channel conductance of 8 pS.   Electron microscopy and cross-linking experiments of the protein   fused to the maltose-binding protein and expressed in Escherichia   coli are consistent with a ****-pentameric organization. Sequence   comparison shows that it possesses a compact structure, with the   absence of the amino-terminal helix, the canonical disulphide   bridge and the large cytoplasmic domain found in eukaryotic   pLGICs. Therefore it embodies a minimal structure required for   signal transduction. These data establish the prokaryotic origin   of the family. Because Gloeobacter violaceus carries out   photosynthesis and proton transport at the cytoplasmic membrane,   this new proton-gated ion channel might contribute to adaptation   to pH change.

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