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PDBsum entry 4ntx
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Transport protein/toxin
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PDB id
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4ntx
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Contents |
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410 a.a.
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60 a.a.
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118 a.a.
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References listed in PDB file
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Key reference
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Title
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X-Ray structure of acid-Sensing ion channel 1-Snake toxin complex reveals open state of a na(+)-Selective channel.
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Authors
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I.Baconguis,
C.J.Bohlen,
A.Goehring,
D.Julius,
E.Gouaux.
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Ref.
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Cell, 2014,
156,
717-729.
[DOI no: ]
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PubMed id
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Abstract
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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 α 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 ∼3.6 Å, 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.
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