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PDBsum entry 2a0l
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Membrane protein
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PDB id
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2a0l
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Contents |
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214 a.a.
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105 a.a.
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116 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 the kvap voltage-Dependent k+ channel and its dependence on the lipid membrane.
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Authors
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S.Y.Lee,
A.Lee,
J.Chen,
R.Mackinnon.
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Ref.
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Proc Natl Acad Sci U S A, 2005,
102,
15441-15446.
[DOI no: ]
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PubMed id
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Abstract
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Voltage-dependent ion channels gate open in response to changes in cell membrane
voltage. This form of gating permits the propagation of action potentials. We
present two structures of the voltage-dependent K(+) channel KvAP, in complex
with monoclonal Fv fragments (3.9 A) and without antibody fragments (8 A). We
also studied KvAP with disulfide cross-bridges in lipid membranes. Analyzing
these data in the context of the crystal structure of Kv1.2 and EPR data on KvAP
we reach the following conclusions: (i) KvAP is similar in structure to Kv1.2
with a very modest difference in the orientation of its voltage sensor; (ii) mAb
fragments are not the source of non-native conformations of KvAP in crystal
structures; (iii) because KvAP contains separate loosely adherent domains, a
lipid membrane is required to maintain their correct relative orientations, and
(iv) the model of KvAP is consistent with the proposal of voltage sensing
through the movement of an arginine-containing helix-turn-helix element at the
protein-lipid interface.
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Figure 2.
Fig. 2. Structure of the KvAP-33HI complex and comparison
with previous KvAP structures. (a) Stereo view of a single KvAP
subunit from the side with extracellular solution above. S1-S4
helices are colored blue. (b) Stereo view of a single KvAP
subunit of the KvAP-6E1 Fab complex (PDB ID code 1ORQ [PDB]
). (c) Comparison with the isolated voltage sensor structure.
Stereo view of a superposition of the isolated voltage sensor
(gold, PDB ID code 1ORS [PDB]
) and the KvAP-Fv complex (blue). The S2 helix (Leu-55 to
Tyr-75) was used for superposition, and the S1 helix is not
shown. Residues Asp-62, Asp-72, Arg-76, Glu-93, and Arg-133,
which are important for channel function, are shown in
ball-and-stick representation.
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Figure 6.
Fig. 6. A model of the KvAP tetramer in the open
conformation. The top-down view (a) and the side view (b) of the
proposed model of the KvAP tetramer in the open conformation.
Each subunit is colored blue, green, gold, and red. This model
is the same as in Fig. 4b but it is shown as a tetramer to show
the position of the voltage sensor relative to the pore.
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