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PDBsum entry 6w0h
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Membrane protein
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PDB id
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6w0h
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Contents |
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219 a.a.
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212 a.a.
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103 a.a.
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PDB id:
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Membrane protein
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Title:
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Closed-gate kcsa soaked in 5mm kcl/5mm bacl2
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Structure:
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Fab heavy chain. Chain: a. Engineered: yes. Fab light chain. Chain: b. Engineered: yes. Ph-gated potassium channel kcsa. Chain: c. Synonym: streptomyces lividans k+ channel,skc1.
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Source:
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Rattus norvegicus. Organism_taxid: 10116. Expressed in: homo sapiens. Expression_system_taxid: 9606. Streptomyces lividans. Organism_taxid: 1916. Gene: kcsa, skc1. Expressed in: escherichia coli. Expression_system_taxid: 562
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Resolution:
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2.60Å
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R-factor:
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0.197
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R-free:
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0.239
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Authors:
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A.Rohaim,L.Gong,J.Li
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Key ref:
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A.Rohaim
et al.
(2020).
Open and Closed Structures of a Barium-Blocked Potassium Channel.
J Mol Biol,
432,
4783-4798.
PubMed id:
DOI:
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Date:
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29-Feb-20
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Release date:
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08-Jul-20
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PROCHECK
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Headers
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References
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No UniProt id for this chain
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DOI no:
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J Mol Biol
432:4783-4798
(2020)
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PubMed id:
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Open and Closed Structures of a Barium-Blocked Potassium Channel.
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A.Rohaim,
L.Gong,
J.Li,
H.Rui,
L.Blachowicz,
B.Roux.
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ABSTRACT
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Barium (Ba2+) is a classic permeant blocker of potassium
(K+) channels. The "external lock-in effect" in barium
block experiments, whereby the binding of external K+ impedes the
forward translocation of the blocker, provides a powerful avenue to investigate
the selectivity of the binding sites along the pore of potassium channels.
Barium block experiments show that the external lock-in site is highly selective
for K+ over Na+. Wild-type KcsA was crystallized in low
K+ conditions, and the crystals were soaked in solutions containing
various concentrations of barium. Structural analysis reveals open and closed
gate conformations of the KcsA channel. Anomalous diffraction experiments show
that Ba2+ primarily binds to the innermost site S4 of the selectivity
filter of the open-gate conformation and also the site S2, but no binding is
detected with the closed-gate conformation. Alchemical free-energy perturbation
calculations indicate that the presence of a Ba2+ ion in the
selectivity filter boosts the specificity of K+ binding relative to
Na+ in the external sites S0-S2.
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Links
