4il4

The pentameric ligand-gated ion channel GLIC in complex with Se-DDM

spinqualitylabelsall models 4il4, resolution 3.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4il4 is a 5 chain structure with sequence from Gloeobacter violaceus PCC 7421. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 3.3Å Ligands: ACT, CL, LSM, NA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT 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. Publication Abstract from PubMed To understand the molecular mechanism of ion permeation in pentameric ligand-gated ion channels (pLGIC), we solved the structure of an open form of GLIC, a prokaryotic pLGIC, at 2.4 A. Anomalous diffraction data were used to place bound anions and cations. This reveals ordered water molecules at the level of two rings of hydroxylated residues (named Ser6' and Thr2') that contribute to the ion selectivity filter. Two water pentagons are observed, a self-stabilized ice-like water pentagon and a second wider water pentagon, with one sodium ion between them. Single-channel electrophysiology shows that the side-chain hydroxyl of Ser6' is crucial for ion translocation. Simulations and electrostatics calculations complemented the description of hydration in the pore and suggest that the water pentagons observed in the crystal are important for the ion to cross hydrophobic constriction barriers. Simulations that pull a cation through the pore reveal that residue Ser6' actively contributes to ion translocation by reorienting its side chain when the ion is going through the pore. Generalization of these findings to the pLGIC family is proposed. Structural basis for ion permeation mechanism in pentameric ligand-gated ion channels.,Sauguet L, Poitevin F, Murail S, Van Renterghem C, Moraga-Cid G, Malherbe L, Thompson AW, Koehl P, Corringer PJ, Baaden M, Delarue M EMBO J. 2013 Feb 12;32(5):728-41. doi: 10.1038/emboj.2013.17. Epub 2013 Feb 12. PMID:23403925 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Ion channels 3D structures

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