title: Association and stoichiometry of K(ATP) channel subunits.
abstract: 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.
authors.affiliation: Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Clement
authors.forename: K
authors.initials: K
authors.lastname: Kunjilwar
authors.forename: G
authors.initials: G
authors.lastname: Gonzalez
authors.forename: M
authors.initials: M
authors.lastname: Schwanstecher
authors.forename: U
authors.initials: U
authors.lastname: Panten
authors.forename: L
authors.initials: L
authors.lastname: Aguilar-Bryan
authors.forename: J
authors.initials: J
authors.lastname: Bryan
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology / Q000502:physiology*; D000345:Affinity Labels; D000818:Animals; D019556:COS Cells / Q000502:physiology; D003981:Diazoxide / Q000494:pharmacology; D005905:Glyburide / Q000031:analogs & derivatives; D006031:Glycosylation; D006639:Histidine / Q000737:chemistry; D015640:Ion Channel Gating / Q000502:physiology; D008970:Molecular Weight; D016296:Mutagenesis / Q000502:physiology; D018408:Patch-Clamp Techniques; D010777:Photochemistry; D015221:Potassium Channels / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000502:physiology; D013453:Sulfonylurea Compounds / Q000494:pharmacology
chemical_list: D000345:Affinity Labels; D015221:Potassium Channels; D011993:Recombinant Fusion Proteins; D013453:Sulfonylurea Compounds; C067320:iodoglibenclamide; D006639:Histidine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D003981:Diazoxide; D005905:Glyburide