3r65 | pdb_00003r65

MthK channel pore E92Q mutant

spinqualitylabelsall models 3r65, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3r65 is a 1 chain structure with sequence from Methanothermobacter thermautotrophicus str. delta h. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: K Related: 3ldc Gene: mthK, MTH_1520 (Methanothermobacter thermautotrophicus str. Delta H) Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed While selective for K, K channels vary significantly among their rate of ion permeation. Here, we probe the effect of steric hindrance and electrostatics within the ion conduction pathway on K permeation in the MthK K channel using structure-based mutagenesis combined with single-channel electrophysiology and X-ray crystallography. We demonstrate that changes in side-chain size and polarity at Ala88, which forms the constriction point of the open MthK pore, have profound effects on single-channel conductance as well as open probability. We also reveal that the negatively charged Glu92s at the intracellular entrance of the open pore form an electrostatic trap, which stabilizes a hydrated K and facilitates ion permeation. This electrostatic attraction is also responsible for intracellular divalent blockage, which renders the channel inward rectified in the presence of Ca(2). In light of the high structural conservation of the selectivity filter, the size and chemical environment differences within the portion of the ion conduction pathway other than the filter are likely the determinants for the conductance variations among K channels. Crucial points within the pore as determinants of K channel conductance and gating.,Shi N, Zeng W, Ye S, Li Y, Jiang Y J Mol Biol. 2011 Aug 5;411(1):27-35. Epub 2011 Apr 30. PMID:21554888 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Potassium Channel

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