title: A strongly inwardly rectifying K+ channel that is sensitive to ATP.
abstract: We have cloned an inwardly rectifying K+ channel from the hamster insulinoma cDNA library and shown that it is inhibited by cytoplasmic ATP. The channel is 90.97% identical to the IRK3 channels cloned from other species, and its mRNA is found primarily in the brain. When expressed in Xenopus oocytes, the channel displays strong inward rectification typical of inward rectifiers. The channel is inhibited reversibly by physiological concentrations of ATP via a mechanism that does not appear to involve ATP hydrolysis, as shown by studies of channels in excised inside-out membrane patches. This effect is antagonized by ADP, again in the physiological range, implying that this channel is sensitive to the index of metabolic state, i.e., the intracellular [ATP]/[ADP] ratio. This channel is different from previously known ATP-sensitive K+ channels, although it may also be stimulated by MgATP, as are other ATP-sensitive K+ channels. The potential physiological significance of these ATP-dependent regulations will be discussed.
authors.affiliation: Howard Hughes Medical Institute, Department of Physiology, University of California, San Francisco 94143-0724, USA.
authors.forename: A
authors.initials: A
authors.lastname: Collins
authors.forename: M S
authors.initials: MS
authors.lastname: German
authors.forename: Y N
authors.initials: YN
authors.lastname: Jan
authors.forename: L Y
authors.initials: LY
authors.lastname: Jan
authors.forename: B
authors.initials: B
authors.lastname: Zhao
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000502:physiology; D006224:Cricetinae; D018076:DNA, Complementary; D005786:Gene Expression Regulation / Q000502:physiology; D007340:Insulinoma; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000235:genetics*; D012680:Sensitivity and Specificity; D014407:Tumor Cells, Cultured / Q000502:physiology; D014981:Xenopus
chemical_list: D018076:DNA, Complementary; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate