Mapping the architecture of the ATP-binding site of the KATP channel subunit Kir6.2.
ATP-sensitive potassium (K(ATP)) channels comprise Kir6.2 and SUR subunits. The site at which ATP binds to mediate K(ATP) channel inhibition lies on Kir6.2, but the potency of block is enhanced by coexpression with SUR1. To assess the structure of the ATP-binding site on Kir6.2, we used a range of adenine nucleotides as molecular measuring sticks to map the internal dimensions of the binding site. We compared their efficacy on Kir6.2-SUR1, and on a truncated Kir6.2 (Kir6.2DeltaC) that expresses in the absence of SUR. We show here that SUR1 modifies the ATP-binding pocket of Kir6.2, by increasing the width of the groove that binds the phosphate tail of ATP, without changing the length of the groove, and by enhancing interaction with the adenine ring.
University Laboratory of Physiology, Parks Road, Oxford OX1 3PT, UK.
Michael
M
Dabrowski
Andrei
A
Tarasov
Frances M
FM
Ashcroft
D018528:ATP-Binding Cassette Transporters; D000227:Adenine Nucleotides / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites; D002478:Cells, Cultured; D005260:Female; D018014:Gene Transfer Techniques; D051379:Mice; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009865:Oocytes; D018408:Patch-Clamp Techniques; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger; D051381:Rats; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D014981:Xenopus; D000099161:Kcnj11 Channel
D018528:ATP-Binding Cassette Transporters; D000227:Adenine Nucleotides; D000255:Adenosine Triphosphate; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D000099161:Kcnj11 Channel; C577508:Abcc8 protein, mouse; C577509:Abcc8 protein, rat