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3‐D structural and functional characterization of the purified K ATP channel complex Kir6.2–SUR1
Author(s) -
Mikhailov Michael V,
Campbell Jeff D,
de Wet Heidi,
Shimomura Kenju,
Zadek Brittany,
Collins Richard F,
Sansom Mark SP,
Ford Robert C,
Ashcroft Frances M
Publication year - 2005
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1038/sj.emboj.7600877
Subject(s) - biology , kir6.2 , sulfonylurea receptor , characterization (materials science) , biochemistry , biophysics , genetics , protein subunit , gene , materials science , nanotechnology
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 Å 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.