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PDBsum entry 1exb
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Metal transport
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PDB id
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1exb
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Contents |
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* Residue conservation analysis
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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 the cytoplasmic beta subunit-T1 assembly of voltage-Dependent k+ channels.
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Authors
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J.M.Gulbis,
M.Zhou,
S.Mann,
R.Mackinnon.
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Ref.
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Science, 2000,
289,
123-127.
[DOI no: ]
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PubMed id
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Abstract
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The structure of the cytoplasmic assembly of voltage-dependent K+ channels was
solved by x-ray crystallography at 2.1 angstrom resolution. The assembly
includes the cytoplasmic (T1) domain of the integral membrane alpha subunit
together with the oxidoreductase beta subunit in a fourfold symmetric T1(4)beta4
complex. An electrophysiological assay showed that this complex is oriented with
four T1 domains facing the transmembrane pore and four beta subunits facing the
cytoplasm. The transmembrane pore communicates with the cytoplasm through
lateral, negatively charged openings above the T1(4)beta4 complex. The
inactivation peptides of voltage-dependent K(+) channels reach their site of
action by entering these openings.
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Figure 1.
Fig. 1. Structure of the T1[4]  [4]
complex. (A) Ribbon representation showing four contact loops
that form the primary interface between the T1 and tetramers.
The T1 tetramer is red and the tetramer
is blue. (B) Molecular detail of a T1 contact loop touching the
subunit
surface (24). (C) Stereoview of a C  trace of
the tetramer
(blue) and T1 tetramer (red) viewed along the four-fold axis and
showing the relative proximity of the NH[2]-termini of each
where inactivation gates are attached. The NADP+ cofactor in
each active site is green. This figure was generated with the
programs O (25), MOLSCRIPT (26), Raster-3D (27), and POVRAY
(28).
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Figure 5.
Fig. 5. Composite model of a voltage-dependent K+ channel. The
subunit
is shown in red, and the subunit is
in blue. The model of the pore region is based on the KcsA K+
channel (30). The structures of the voltage-sensing region and
connectors are unknown (depicted schematically). An
NH[2]-terminal inactivation peptide is shown entering a lateral
opening to gain access to the pore. Proposed locations of amino
acids 273 to 275 on the T1-S1 linker are shown (black asterisks)
with the location of Val247 on the T1 domain surface (green
asterisks).
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The above figures are
reprinted
by permission from the AAAs:
Science
(2000,
289,
123-127)
copyright 2000.
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