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Inwardly rectifying current-voltage relationship of small-conductance Ca2+-activated K+ channels rendered by intracellular divalent cation blockade.
Soh H
,
Park CS
.
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Small conductance Ca2+-activated K+ channels (SK(Ca) channels) are a group of K+-selective ion channels activated by submicromolar concentrations of intracellular Ca2+ independent of membrane voltages. We expressed a cloned SK(Ca) channel, rSK2, in Xenopus oocytes and investigated the effects of intracellular divalent cations on the current-voltage (I-V) relationship of the channels. Both Mg2+ and Ca2+ reduced the rSK2 channel currents in voltage-dependent manners from the intracellular side and thus rectified the I-V relationship at physiological concentration ranges. The apparent affinity of Mg2+ was changed as a function of both transmembrane voltage and intracellular Ca2+ concentration. Extracellular K+ altered the voltage dependence as well as the apparent affinities of Mg2+ binding from intracellular side. Thus, the inwardly rectifying I-V relationship of SK(Ca) channels is likely due to the voltage-dependent blockade of intracellular divalent cations and that the binding site is located within the ion-conducting pathway. Therefore, intracellular Ca2+ modulates the permeation characteristics of SK(Ca) channels by altering the I-V relationship as well as activates the channel by interacting with the gating machinery, calmodulin, and SK(Ca) channels can be considered as Ca2+-activated inward rectifier K+ channels.
ARMSTRONG,
ANOMALOUS RECTIFICATION IN THE SQUID GIANT AXON INJECTED WITH TETRAETHYLAMMONIUM CHLORIDE.
1965, Pubmed
ARMSTRONG,
ANOMALOUS RECTIFICATION IN THE SQUID GIANT AXON INJECTED WITH TETRAETHYLAMMONIUM CHLORIDE.
1965,
Pubmed
Bezanilla,
Negative conductance caused by entry of sodium and cesium ions into the potassium channels of squid axons.
1972,
Pubmed
Cao,
Activation of recombinant human SK4 channels by metal cations.
1999,
Pubmed
Doupnik,
The inward rectifier potassium channel family.
1995,
Pubmed
Ha,
Functional characteristics of two BKCa channel variants differentially expressed in rat brain tissues.
2000,
Pubmed
,
Xenbase
Hille,
Ionic selectivity of Na and K channels of nerve membranes.
1975,
Pubmed
Ishii,
Determinants of apamin and d-tubocurarine block in SK potassium channels.
1997,
Pubmed
,
Xenbase
Keen,
Domains responsible for constitutive and Ca(2+)-dependent interactions between calmodulin and small conductance Ca(2+)-activated potassium channels.
1999,
Pubmed
,
Xenbase
Köhler,
Small-conductance, calcium-activated potassium channels from mammalian brain.
1996,
Pubmed
,
Xenbase
Lancaster,
Calcium activates two types of potassium channels in rat hippocampal neurons in culture.
1991,
Pubmed
Liman,
Subunit stoichiometry of a mammalian K+ channel determined by construction of multimeric cDNAs.
1992,
Pubmed
,
Xenbase
Lu,
Electrostatic tuning of Mg2+ affinity in an inward-rectifier K+ channel.
1994,
Pubmed
,
Xenbase
Ozawa,
Metal ion selectivity for formation of the calmodulin-metal-target peptide ternary complex studied by surface plasmon resonance spectroscopy.
1999,
Pubmed
Park,
Divalent cation selectivity in a cyclic nucleotide-gated ion channel.
1995,
Pubmed
,
Xenbase
Regehr,
Calcium concentration dynamics produced by synaptic activation of CA1 hippocampal pyramidal cells.
1992,
Pubmed
Spassova,
Coupled ion movement underlies rectification in an inward-rectifier K+ channel.
1998,
Pubmed
,
Xenbase
Vergara,
Calcium-activated potassium channels.
1998,
Pubmed
Woodhull,
Ionic blockage of sodium channels in nerve.
1973,
Pubmed
Xia,
Mechanism of calcium gating in small-conductance calcium-activated potassium channels.
1998,
Pubmed
,
Xenbase
