Abstract
Virtually all cells in all eukaryotic organisms express ion channels of the ClC type, the only known molecular family of chloride-ion-selective channels. The diversity of ClC channels highlights the multitude and range of functions served by gated chloride-ion conduction in biological membranes, such as controlling electrical excitability in skeletal muscle, maintaining systemic blood pressure, acidifying endosomal compartments, and regulating electrical responses of GABA (γ-aminobutyric acid)-containing interneurons in the central nervous system1. Previously, we expressed and purified a prokaryotic ClC channel homologue2. Here we report the formation of two-dimensional crystals of this ClC channel protein reconstituted into phospholipid bilayer membranes. Cryo-electron microscopic analysis of these crystals yields a projection structure at 6.5 Å resolution, which shows off-axis water-filled pores within the dimeric channel complex.
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Acknowledgements
We are grateful to R. Henderson for making facilities at the MRC, including the Hitachi microscope, available to us for low-dose experiments, to J. Berriman for help and hand-holding, and to T. Walz for crucial advice on crystallization. We also acknowledge D. Pheasant and L. Melanson for technical assistance. Support was provided in part by a grant to J.A.M. from the NIH.
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Mindell, J., Maduke, M., Miller, C. et al. Projection structure of a ClC-type chloride channel at 6.5 Å resolution. Nature 409, 219–223 (2001). https://doi.org/10.1038/35051631
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DOI: https://doi.org/10.1038/35051631
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