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Publication Abstract from PubMed

Acid-sensing ion channels (ASICs) detect extracellular protons produced during inflammation or ischemic injury and belong to the superfamily of degenerin/epithelial sodium channels. Here, we determine the cocrystal structure of chicken ASIC1a with MitTx, a pain-inducing toxin from the Texas coral snake, to define the structure of the open state of ASIC1a. In the MitTx-bound open state and in the previously determined low-pH desensitized state, TM2 is a discontinuous alpha helix in which the Gly-Ala-Ser selectivity filter adopts an extended, belt-like conformation, swapping the cytoplasmic one-third of TM2 with an adjacent subunit. Gly 443 residues of the selectivity filter provide a ring of three carbonyl oxygen atoms with a radius of approximately 3.6 A, presenting an energetic barrier for hydrated ions. The ASIC1a-MitTx complex illuminates the mechanism of MitTx action, defines the structure of the selectivity filter of voltage-independent, sodium-selective ion channels, and captures the open state of an ASIC.

X-ray structure of Acid-sensing ion channel 1-snake toxin complex reveals open state of a na(+)-selective channel.,Baconguis I, Bohlen CJ, Goehring A, Julius D, Gouaux E Cell. 2014 Feb 13;156(4):717-29. doi: 10.1016/j.cell.2014.01.011. Epub 2014 Feb, 6. PMID:24507937^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.