Affiliation:
1. Howard Hughes Medical Institute, Laboratory of Molecular Neurobiology and Biophysics, Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Abstract
Voltage-dependent ion channels contain voltage sensors that allow them to switch between nonconductive and conductive states over the narrow range of a few hundredths of a volt. We investigated the mechanism by which these channels sense cell membrane voltage by determining the x-ray crystal structure of a mammalian
Shaker
family potassium ion (K
+
) channel. The voltage-dependent K
+
channel Kv1.2 grew three-dimensional crystals, with an internal arrangement that left the voltage sensors in an apparently native conformation, allowing us to reach three important conclusions. First, the voltage sensors are essentially independent domains inside the membrane. Second, they perform mechanical work on the pore through the S4-S5 linker helices, which are positioned to constrict or dilate the S6 inner helices of the pore. Third, in the open conformation, two of the four conserved Arg residues on S4 are on a lipid-facing surface and two are buried in the voltage sensor. The structure offers a simple picture of how membrane voltage influences the open probability of the channel.
Publisher
American Association for the Advancement of Science (AAAS)
Cited by
897 articles.
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