RRC ID 39247
著者 Oishi K, Omori K, Ohyama H, Shingu K, Matsuda H.
タイトル Neutralization of aspartate residues in the murine inwardly rectifying K+ channel IRK1 affects the substate behaviour in Mg2+ block.
ジャーナル J Physiol
Abstract 1. To investigate the molecular basis of the sublevels induced in the outward current during block by intracellular Mg2+, single-channel currents through inwardly rectifying K+ (IRK1) channels were studied. 2. cDNA encoding a functional murine IRK1 channel was transfected into COS-1 cells (a Green Monkey kidney cell line) using the liposome method, and voltage clamp experiments were done after 48-72 h. 3. Intracellular Mg2+ at micromolar concentrations induced sublevels in the outward current at one-third and two-thirds of the unitary amplitude seen in wild-type channels. Replacing Asp 172 with Asn (D172N) and Gln (D172Q) abolished these sublevels, i.e. the channel showed only the fully open and fully blocked states. 4. Both mutations reduced the Mg2+ sensitivity of the channel at 2 microM Mg2+. However, the Mg2+ sensitivity did not differ significantly at higher concentrations (10 microM) and voltages (+70 mV). 5. Channels expressed from D172E showed the sublevels, indicating that a negative charge is indispensable to the substate behaviour. 6. Channels from tandem tetramers of IRK1 with one and two D172N mutant subunits mainly showed sublevels with two-thirds amplitude, while those from tetramers with three D172N mutant subunits showed no sublevels. 7. These findings suggest that differences in Mg2+ binding patterns lead to different conductive states in a single-barrelled channel.
巻・号 510 ( Pt 3)(Pt 3)
ページ 675-83
公開日 1998-8-1
DOI 10.1111/j.1469-7793.1998.675bj.x
PMID 9660884
PMC PMC2231070
MeSH Animals Aspartic Acid / physiology* Cell Line DNA / biosynthesis DNA / genetics Electric Stimulation Electrophysiology Haplorhini Magnesium / pharmacology* Membrane Potentials / physiology Mice Mutagenesis, Site-Directed Patch-Clamp Techniques Potassium Channel Blockers* Potassium Channels / genetics Potassium Channels / metabolism* Potassium Channels, Inwardly Rectifying*
IF 4.547
引用数 20
WOS 分野 PHYSIOLOGY NEUROSCIENCES
リソース情報
ヒト・動物細胞