Abstract
Voltage-dependent ion channels serve as field-effect transistors by opening a gate in response to membrane voltage changes. The gate's response to voltage is mediated by voltage sensors, which are arginine-containing structures that must move with respect to the membrane electric field. We have analysed by electron microscopy a voltage-dependent K+ channel from Aeropyrum pernix (KvAP). Fab fragments were attached to 'voltage sensor paddles' and identified in the electron microscopy map at 10.5 Å resolution. The extracellular surface location of the Fab fragments in the map is consistent with the membrane-depolarized, open conformation of the channel in electrophysiological experiments. Comparison of the map with a crystal structure demonstrates that the voltage sensor paddles are 'up' (that is, near the channel's extracellular surface) and situated at the protein-lipid interface. This finding supports the hypothesis that in response to changes in voltage the sensors move at the protein-lipid interface rather than in a gating pore surrounded by protein.
Original language | English (US) |
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Pages (from-to) | 806-810 |
Number of pages | 5 |
Journal | Nature |
Volume | 430 |
Issue number | 7001 |
DOIs | |
State | Published - Aug 12 2004 |
ASJC Scopus subject areas
- General