Structural highlights
Function[GLIC_GLOVI] Cationic channel with similar permeabilities for Na(+) and K(+), that is activated by an increase of the proton concentration on the extracellular side. Displays no permeability for chloride ions. Shows slow kinetics of activation, no desensitization and a single channel conductance of 8 pS. Might contribute to adaptation to external pH change.[1] Publication Abstract from PubMedPentameric ligand-gated ion channels mediate signal transduction through conformational transitions between closed-pore and open-pore states. To stabilize a closed conformation of GLIC, a bacterial proton-gated homolog from Gloeobacter violaceus whose open structure is known, we separately generated either four cross-links or two single mutations. We found all six mutants to be in the same 'locally closed' conformation using X-ray crystallography, sharing most of the features of the open form but showing a locally closed pore as a result of a concerted bending of all of its M2 helices. The mutants adopt several variant conformations of the M2-M3 loop, and in all cases an interacting lipid that is observed in the open form disappears. A single cross-linked mutant is functional, according to electrophysiology, and the locally closed structure of this mutant indicates that it has an increased flexibility. Further cross-linking, accessibility and molecular dynamics data suggest that the locally closed form is a functionally relevant conformation that occurs during allosteric gating transitions. A locally closed conformation of a bacterial pentameric proton-gated ion channel.,Prevost MS, Sauguet L, Nury H, Van Renterghem C, Huon C, Poitevin F, Baaden M, Delarue M, Corringer PJ Nat Struct Mol Biol. 2012 May 13. doi: 10.1038/nsmb.2307. PMID:22580559[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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