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Atomic scale structure and functional models of voltage-gated potassium channels
1Laboratory of Mathematical Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.
Biophysical Journal
|April 1, 1992
Summary
Mutagenesis experiments reveal the S5-S6 segment forms the ion-selective pore in voltage-gated ion channels. New atomic models show a beta-barrel structure and a helical screw mechanism for channel gating.
Area of Science:
- Molecular Biology
- Biophysics
- Structural Biology
Background:
- Voltage-gated ion channels are crucial for cellular electrical signaling.
- Previous models lacked atomic-level detail of the transmembrane region.
- The S5-S6 segment's role in ion selectivity was hypothesized.
Purpose of the Study:
- To refine models of voltage-gated ion channel protein folding.
- To develop atomic-scale models of the Shaker A K+ channel transmembrane region.
- To elucidate the mechanisms of channel gating and inactivation.
Main Methods:
- Utilized recent mutagenesis data.
- Developed atomic-scale models of the Shaker A K+ channel.
- Modeled protein conformational changes during gating.
Main Results:
- Confirmed S5-S6 segment forms the ion-selective pore.
- Proposed an atomic model with a beta-barrel ion-selective region and a larger inner pore.
- Modeled activation gating via a "helical screw" mechanism of S4 segments.
- Identified a voltage-independent conformational change in linker segments.
- Modeled NH2-terminal alpha-helix as an inactivation gate.
Conclusions:
- The S5-S6 segment is critical for ion selectivity in voltage-gated channels.
- Atomic models provide detailed insights into channel structure and function.
- The "helical screw" mechanism explains activation gating.
- Distinct conformational changes govern channel gating and inactivation.