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Neuron. 1997 May;18(5):827-38.

Association and stoichiometry of K(ATP) channel subunits.

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Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.


ATP-sensitive potassium channels (K(ATP) channels) are heteromultimers of sulfonylurea receptors (SUR) and inwardly rectifying potassium channel subunits (K(IR)6.x) with a (SUR-K(IR)6.x)4 stoichiometry. Association is specific for K(IR)6.x and affects receptor glycosylation and cophotolabeling of K(IR)6.x by 125I-azidoglibenclamide. Association produces digitonin stable complexes with an estimated mass of 950 kDa. These complexes can be purified by lectin chromatography or by using Ni2(+)-agarose and a his-tagged SUR1. Expression of SUR1 approximately (K(IR)6.2)i fusion constructs shows that a 1:1 SUR1:K(IR)6.2 stoichiometry is both necessary and sufficient for assembly of active K(ATP) channels. Coexpression of a mixture of strongly and weakly rectifying triple fusion proteins, rescued by SUR1, produced the three channel types expected of a tetrameric pore.

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