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ATP-sensitive potassium (K(ATP)) channels conduct potassium ions across cell membranes and thereby couple cellular energy metabolism to membrane electrical activity. Here, we report the heterologous expression and purification of a functionally active K(ATP) channel complex composed of pore-forming Kir6.2 and regulatory SUR1 subunits, and determination of its structure at 18 A resolution by single-particle electron microscopy. The purified channel shows ATP-ase activity similar to that of ATP-binding cassette proteins related to SUR1, and supports Rb(+) fluxes when reconstituted into liposomes. It has a compact structure, with four SUR1 subunits embracing a central Kir6.2 tetramer in both transmembrane and cytosolic domains. A cleft between adjacent SUR1s provides a route by which ATP may access its binding site on Kir6.2. The nucleotide-binding domains of adjacent SUR1 appear to interact, and form a large docking platform for cytosolic proteins. The structure, in combination with molecular modelling, suggests how SUR1 interacts with Kir6.2.

Original publication

DOI

10.1038/sj.emboj.7600877

Type

Journal article

Journal

EMBO J

Publication Date

07/12/2005

Volume

24

Pages

4166 - 4175

Keywords

ATP-Binding Cassette Transporters, Amino Acid Sequence, Animals, Cryoelectron Microscopy, Mice, Molecular Sequence Data, Potassium Channels, Potassium Channels, Inwardly Rectifying, Protein Structure, Tertiary, Rats, Receptors, Drug, Recombinant Fusion Proteins, Sulfonylurea Receptors