The intrinsic gating of inward rectifier K+ channels expressed from the murine IRK1 gene depends on voltage, K+ and Mg2

• Published in: The Journal of physiology Vol. 475; no. 1; pp. 1 - 7
• Main Authors: Stanfield, P R, Davies, N W, Shelton, P A, Khan, I A, Brammar, W J, Standen, N B, Conley, E C
• Format: Journal Article
• Language: English
• Published: Oxford The Physiological Society 15.02.1994; Blackwell
• Subjects: Animals; Base Sequence; Biological and medical sciences; Cell membranes. Ionic channels. Membrane pores; Cell structures and functions; Cells, Cultured; Cloning, Molecular; Electrophysiology; Fundamental and applied biological sciences. Psychology; Genome; Introns; Ion Channel Gating - physiology; Leukemia, Erythroblastic, Acute - metabolism; Magnesium - physiology; Mice; Molecular and cellular biology; Molecular Sequence Data; Polymerase Chain Reaction; Potassium - physiology; Potassium Channels - drug effects; Potassium Channels - metabolism; Rodentia; Electrophysiology; Ionic channel; Ionic current; Gene expression; In vitro; Vertebrata; Mammalia; Cell line; Mouse; Magnesium; Membrane potential; Molecular cloning; Potassium
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.1994.sp020044

1. We describe the cloning of the inward rectifier K+ channel IRK1 from genomic DNA of mouse; the gene is intronless. 2. The IRK1 gene can be stably expressed in murine erythroleukaemia (MEL) cells. Such transfected cells show inward rectification under whole-cell recording. 3. Channels encoded by the IRK1 gene have an intrinsic gating that depends on voltage and [K+]o. Rate constants are reduced e-fold as the driving force on K+(V-EK) is reduced by 24.1 mV. 4. Removal of intracellular Mg2+ permits brief outward currents under depolarization. The instantaneous current-voltage relation may be fitted by an appropriate constant field expression. 5. Removal of intracellular Mg2+ speeds channel closure at positive voltages. In nominally zero [Mg2+]i, rate constants for the opening and closing of channels, processes which are first order, are similar to those of native channels.