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PDBsum entry 4jtc
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Transport protein/toxin
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PDB id
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4jtc
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Contents |
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326 a.a.
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386 a.a.
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363 a.a.
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37 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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Structure of a pore-Blocking toxin in complex with a eukaryotic voltage-Dependent k(+) channel.
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Authors
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A.Banerjee,
A.Lee,
E.Campbell,
R.Mackinnon.
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Ref.
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Elife, 2013,
2,
e00594.
[DOI no: ]
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PubMed id
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Abstract
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Pore-blocking toxins inhibit voltage-dependent K(+) channels (Kv channels) by
plugging the ion-conduction pathway. We have solved the crystal structure of
paddle chimera, a Kv channel in complex with charybdotoxin (CTX), a
pore-blocking toxin. The toxin binds to the extracellular pore entryway without
producing discernable alteration of the selectivity filter structure and is
oriented to project its Lys27 into the pore. The most extracellular K(+) binding
site (S1) is devoid of K(+) electron-density when wild-type CTX is bound, but
K(+) density is present to some extent in a Lys27Met mutant. In crystals with
Cs(+) replacing K(+), S1 electron-density is present even in the presence of
Lys27, a finding compatible with the differential effects of Cs(+) vs K(+) on
CTX affinity for the channel. Together, these results show that CTX binds to a
K(+) channel in a lock and key manner and interacts directly with conducting
ions inside the selectivity filter.
DOI:http://dx.doi.org/10.7554/eLife.00594.001.
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