Properties of cloned ATP-sensitive K+ currents expressed in Xenopus oocytes. by Gribble, F, Ashfield, R, Ammälä, C, Ashcroft, F

“…We have studied the electrophysiological properties of cloned ATP-sensitive K+ channels (KATP channels) heterologously expressed in Xenopus oocytes. This channel comprises a sulphonylurea receptor subunit (SUR) and an inwardly rectifying K+ channel subunit (Kir). 2. …”

Expression of the cloned beta-cell ATP-sensitive potassium channel in Xenopus oocytes by Gribble, F, Ashfield, R, Ashcroft, F

Pyridine nucleotide regulation of the KATP channel Kir6.2/SUR1 expressed in Xenopus oocytes. by Dabrowski, M, Trapp, S, Ashcroft, F

“…We therefore investigated whether NAD and NADP interact with both Kir6.2 and SUR1 subunits of the KATP channel by comparing the potency of these agents on recombinant Kir6.2DeltaC and Kir6.2/SUR1 channels expressed in Xenopus oocytes. Our results show that, at physiological concentrations, NAD and NADP interact with the nucleotide inhibitory site of Kir6.2 to inhibit Kir6.2/SUR1 currents. …”

The interaction of nucleotides with the tolbutamide block of cloned ATP-sensitive K+ channel currents expressed in Xenopus oocytes: a reinterpretation. by Gribble, F, Tucker, S, Ashcroft, F

“…We have examined the mechanism by which nucleotides modulate the tolbutamide block of the beta-cell ATP-sensitive K+ channel (KATP channel), using wild-type and mutant KATP channels heterologously expressed in Xenopus oocytes. This channel is composed of sulphonylurea receptor (SUR1) and pore-forming (Kir6.2) subunits. 2. …”

A cytosolic factor that inhibits KATP channels expressed in Xenopus oocytes by impairing Mg-nucleotide activation by SUR1. by Tammaro, P, Ashcroft, F

“…Wild-type (Kir6.2/SUR1) K(ATP) channels heterologously expressed in Xenopus oocytes give rise to very small inward currents in cell-attached patches. …”

MgADP hydrolysis is required for MgADP activation of the cloned beta-cell K-ATP channel expressed in Xenopus oocytes by Gribble, F, Tucker, S, Ashcroft, F

Expression of K channels in Xenopus laevis oocytes injected with poly(A+) mRNA from the insulin-secreting beta-cell line, HIT T15. by Ashcroft, F, Ashcroft, S, Berggren, P, Betzholz, C, Rorsman, P, Trube, G, Welsh, M

“…Two types of exogenous K channel were identified in Xenopus laevis oocytes injected with poly(A+) mRNA from the insulin-secreting cell line HIT T15. …”

Binding of sulphonylureas to plasma proteins – a KATP channel perspective by Proks, P, Kramer, H, Haythorne, E, Ashcroft, F

“…KATP currents from mouse pancreatic β-cells and Xenopus oocytes were measured using the patch-clamp technique. …”

Potent and selective activation of the pancreatic beta-cell type K(ATP) channel by two novel diazoxide analogues. by Dabrowski, M, Larsen, T, Ashcroft, F, Bondo Hansen, J, Wahl, P

“…METHODS: We studied the effects of these compounds on whole-cell currents through cloned K(ATP) channels expressed in Xenopus oocytes or mammalian cells (HEK293). We also used inside-out macropatches excised from Xenopus oocytes. …”

Effect of repaglinide on cloned beta cell, cardiac and smooth muscle types of ATP-sensitive potassium channels. by Dabrowski, M, Wahl, P, Holmes, W, Ashcroft, F

“…METHODS: The action of the drug was studied by whole-cell current recordings of KATP channels expressed either in Xenopus oocytes or mammalian cells (HEK293). We also used inside-out macropatches excised from Xenopus oocytes for detailed analysis of repaglinide action. …”

Characterization of two novel forms of the rat sulphonylurea receptor SUR1A2 and SUR1BDelta31. by Gros, L, Trapp, S, Dabrowski, M, Ashcroft, F, Bataille, D, Blache, P

“…Coinjection of SUR1A2 plus Kir6.2 into Xenopus oocytes or expression of a SUR1A2-Kir6.2 tandem in HEK-293 cells yielded large currents with characteristics similar to the wild-type K(ATP) channel. 3. …”

A conserved tryptophan at the membrane-water interface acts as a gatekeeper for Kir6.2/SUR1 channels and causes neonatal diabetes when mutated. by Männikkö, R, Stansfeld, P, Ashcroft, A, Hattersley, A, Sansom, MS, Ellard, S, Ashcroft, F

“…The functional effects of mutations at residue 68 of Kir6.2 were studied by heterologous expression in Xenopus oocytes, and by homology modelling. We found the Kir6.2-W68R mutation causes a small reduction in ATP inhibition in the heterozygous state and an increase in the whole-cell KATP current. …”

Expression of functionally active ATP-sensitive K-channels in insect cells using baculovirus. by Mikhailov, M, Proks, P, Ashcroft, F, Ashcroft, S

“…Channel activity was also obtained on expression of a C-terminally truncated Kir6.2 (Kir6.2 deltaC26): these channels were blocked by ATP but were insensitive to sulphonylureas. In contrast to Xenopus oocytes and mammalian cells the full length Kir6.2 also gave rise to active channels in Sf9 cells when expressed alone. …”

Heteromeric channel formation and Ca(2+)-free media reduce the toxic effect of the weaver Kir 3.2 allele. by Tucker, S, Pessia, M, Moorhouse, A, Gribble, F, Ashcroft, F, Maylie, J, Adelman, J

“…Recent genetic studies of weaver mice have identified a mutation resulting in an amino acid substitution (G156S) in the pore of the inwardly rectifying potassium channel subunit Kir 3.2. When expressed in Xenopus oocytes the weaver mutation alters channel selectivity from a potassium-selective to a nonspecific cation-selective pore. …”

A gating mutation at the internal mouth of the Kir6.2 pore is associated with DEND syndrome. by Proks, P, Girard, C, Haider, S, Gloyn, A, Hattersley, A, Sansom, MS, Ashcroft, F

“…We investigated the functional effects of the I296L mutation by expressing wild-type or mutant Kir6.2/SUR1 channels in Xenopus oocytes. The mutation caused a marked increase in resting whole-cell K(ATP) currents by reducing channel inhibition by ATP, in both homomeric and simulated heterozygous states. …”

Functional analysis of two Kir6.2 (KCNJ11) mutations, K170T and E322K, causing neonatal diabetes. by Tarasov, A, Girard, C, Larkin, B, Tammaro, P, Flanagan, SE, Ellard, S, Ashcroft, F

“…K(ATP) channels were expressed in Xenopus oocytes, and the heterozygous state was simulated by coexpression of wild-type and mutant Kir6.2 with SUR1 (the beta cell type of sulphonylurea receptor (SUR)). …”

A novel method for measurement of submembrane ATP concentration. by Gribble, F, Loussouarn, G, Tucker, S, Zhao, C, Nichols, C, Ashcroft, F

“…We show here that mutant ATP-sensitive K(+) channels can be used to measure [ATP](sm) by comparing the increase in current amplitude on patch excision with the ATP dose-response curve. In Xenopus oocytes, [ATP](sm) was 4.6 +/- 0.3 mm (n = 29) under resting conditions, slightly higher than that measured for the bulk cytoplasm (2.3 mm). …”

A novel mutation causing DEND syndrome: a treatable channelopathy of pancreas and brain. by Shimomura, K, Horster, F, De Wet, H, Flanagan, SE, Ellard, S, Hattersley, A, Wolf, N, Ashcroft, F, Ebinger, F

“…We carried out electrophysiologic analysis of wild-type and mutant K(ATP) channels heterologously expressed in Xenopus oocytes. RESULTS: We identified a novel Kir6.2 mutation (I167L) causing DEND syndrome. …”

The antimalarial agent mefloquine inhibits ATP-sensitive K-channels. by Gribble, F, Davis, T, Higham, C, Clark, A, Ashcroft, F

“…Macroscopic K(ATP) currents were studied in inside-out patches excised from Xenopus oocytes expressing cloned K(ATP) channels. …”

Interaction of vanadate with the cloned beta cell K(ATP) channel. by Proks, P, Ashfield, R, Ashcroft, F

“…We explored the effect of vanadate (2 mM), in the absence and presence of magnesium nucleotides, on different types of cloned K(ATP) channels expressed in Xenopus oocytes. Currents were recorded from inside-out patches. …”