title: Reconstitution and partial purification of the glibenclamide-sensitive, ATP-dependent K+ channel from rat liver and beef heart mitochondria.
abstract: The transport properties of mitochondria are such that net potassium flux across the inner membrane determines mitochondrial volume. It has been known that K+ uptake is mediated by diffusive leak driven by the high electrical membrane potential maintained by redox-driven, electrogenic proton ejection and that regulated K+ efflux is mediated by an 82-kDa inner membrane K+/H+ antiporter. There is also long-standing suggestive evidence for the existence of an inner membrane protein designed to catalyze electrophoretic K+ uptake into mitochondria. We report reconstitution of a highly purified inner membrane protein fraction from rat liver and beef heart mitochondria that catalyzes electrophoretic K+ flux in liposomes and channel activity in planar lipid bilayers. The unit conductance of the channel at saturating [K+] is about 30 pS. Reconstituted K+ flux is inhibited with high affinity by ATP and ADP in the presence of divalent cations and by glibenclamide in the absence of divalent cations. The mitochondrial ATP-dependent K+ channel is selective for K+, with a Km of 32 mM, and does not transport Na+. K+ transport depends on voltage in a manner consistent with a channel activity that is not voltage-regulated. Thus, the mitochondrial ATP-dependent K+ channel exhibits properties that are remarkably similar to those of the ATP-dependent K+ channels of plasma membranes.
authors: Department of Pharmacology, Medical College of Ohio, Toledo 43699.
authors: P
authors: P
authors: Paucek
authors: G
authors: G
authors: Mironova
authors: F
authors: F
authors: Mahdi
authors: A D
authors: AD
authors: Beavis
authors: G
authors: G
authors: Woldegiorgis
authors: K D
authors: KD
authors: Garlid
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002417:Cattle; D002848:Chromatography, DEAE-Cellulose; D004305:Dose-Response Relationship, Drug; D004553:Electric Conductivity; D004591:Electrophoresis, Polyacrylamide Gel; D005905:Glyburide / Q000494:pharmacology*; D008051:Lipid Bilayers; D008274:Magnesium / Q000494:pharmacology; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000378:metabolism*; D008970:Molecular Weight; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D013367:Submitochondrial Particles / Q000378:metabolism*
chemical_list: D008051:Lipid Bilayers; D008565:Membrane Proteins; D015221:Potassium Channels; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D008274:Magnesium; D011188:Potassium; D005905:Glyburide; D002118:Calcium