Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Pflugers Arch
1996 Jun 01;4322:301-12. doi: 10.1007/s004240050137.
Show Gene links
Show Anatomy links
Extracellular Mg2+ regulates activation of rat eag potassium channel.
Terlau H
,
Ludwig J
,
Steffan R
,
Pongs O
,
Stühmer W
,
Heinemann SH
.
???displayArticle.abstract???
The rat homologue of Drosophila ether à gogo cDNA (rat eag) encodes voltage-activated potassium (K) channels with distinct activation properties. Using the Xenopus expression system, we examined the importance of extracellular Mg2+ on the activation of rat eag. Extracellular Mg2+ at physiological concentrations dramatically slowed the activation in a dose- and voltage-dependent manner. Other divalent cations exerted similar effects on the activation kinetics that correlated with their enthalpy of hydration. Lowering the external pH also resulted in a slowing of the activation. Protons competed with Mg2+ as the effect of Mg2+ was abolished at low pH. A kinetic model for rat eag activation was derived from the data indicating that all four channel subunits undergo a Mg2+-dependent conformational transition prior to final channel activation. The strong dependence of rat eag activation on both the resting potential and the extracellular Mg2+ concentration constitutes a system for fine-tuning K channel availability in neuronal cells.
COLE,
Potassium ion current in the squid giant axon: dynamic characteristic.
1960, Pubmed
COLE,
Potassium ion current in the squid giant axon: dynamic characteristic.
1960,
Pubmed
Gilly,
Divalent cations and the activation kinetics of potassium channels in squid giant axons.
1982,
Pubmed
Good,
Hydrogen ion buffers.
1972,
Pubmed
HODGKIN,
A quantitative description of membrane current and its application to conduction and excitation in nerve.
1952,
Pubmed
Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed
Ishihara,
The Mg2+ block and intrinsic gating underlying inward rectification of the K+ current in guinea-pig cardiac myocytes.
1989,
Pubmed
Lansman,
Blockade of current through single calcium channels by Cd2+, Mg2+, and Ca2+. Voltage and concentration dependence of calcium entry into the pore.
1986,
Pubmed
Liman,
Subunit stoichiometry of a mammalian K+ channel determined by construction of multimeric cDNAs.
1992,
Pubmed
,
Xenbase
Ludewig,
A site accessible to extracellular TEA+ and K+ influences intracellular Mg2+ block of cloned potassium channels.
1993,
Pubmed
Ludwig,
Functional expression of a rat homologue of the voltage gated either á go-go potassium channel reveals differences in selectivity and activation kinetics between the Drosophila channel and its mammalian counterpart.
1994,
Pubmed
,
Xenbase
MacKinnon,
Determination of the subunit stoichiometry of a voltage-activated potassium channel.
1991,
Pubmed
,
Xenbase
Matsuda,
Ohmic conductance through the inwardly rectifying K channel and blocking by internal Mg2+.
,
Pubmed
Mayer,
Voltage-dependent block by Mg2+ of NMDA responses in spinal cord neurones.
,
Pubmed
McCormack,
A characterization of the activating structural rearrangements in voltage-dependent Shaker K+ channels.
1994,
Pubmed
Methfessel,
Patch clamp measurements on Xenopus laevis oocytes: currents through endogenous channels and implanted acetylcholine receptor and sodium channels.
1986,
Pubmed
,
Xenbase
Nowak,
Magnesium gates glutamate-activated channels in mouse central neurones.
,
Pubmed
Pusch,
Open-channel block of Na+ channels by intracellular Mg2+.
1990,
Pubmed
,
Xenbase
Pusch,
Intracellular magnesium blocks sodium outward currents in a voltage- and dose-dependent manner.
1989,
Pubmed
,
Xenbase
Rudy,
Diversity and ubiquity of K channels.
1988,
Pubmed
Shrager,
Ionic conductance changes in voltage clamped crayfish axons at low pH.
1974,
Pubmed
Spires,
Chemical properties of the divalent cation binding site on potassium channels.
1992,
Pubmed
Spires,
Modulation of potassium channel gating by external divalent cations.
1994,
Pubmed
Spires,
Voltage-independent gating transitions in squid axon potassium channels.
1995,
Pubmed
Stühmer,
Electrophysiological recording from Xenopus oocytes.
1992,
Pubmed
,
Xenbase
Stühmer,
Potassium channels expressed from rat brain cDNA have delayed rectifier properties.
1988,
Pubmed
,
Xenbase
Zagotta,
Shaker potassium channel gating. III: Evaluation of kinetic models for activation.
1994,
Pubmed
,
Xenbase
