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Unitary conductance variation in Kir2.1 and in cardiac inward rectifier potassium channels.
Picones A, Keung E, Timpe LC.
???displayArticle.abstract??? Kir2.1 (IRK1) is the complementary DNA for a component of a cardiac inwardly rectifying potassium channel. When Kir2.1 is expressed in Xenopus oocytes or human embryonic kidney (HEK) cells (150 mM external KCl), the unitary conductances form a broad distribution, ranging from 2 to 33 pS. Channels with a similarly broad distribution of unitary conductance amplitudes are also observed in recordings from adult mouse cardiac myocytes under similar experimental conditions. In all three cell types channels with conductances smaller, and occasionally larger, than the ~30 pS ones are found in the same patches as the ~30 pS openings, or in patches by themselves. The unitary conductances in patches with a single active channel are stable for the durations of the recordings. Channels of all amplitudes share several biophysical characteristics, including inward rectification, voltage sensitivity of open probability, sensitivity of open probability to external divalent cations, shape of the open channel i-V relation, and Cs(+) block. The only biophysical difference found between large and small conductance channels is that the rate constant for Cs(+) block is reduced for the small-amplitude channels. The unblocking rate constant is similar for channels of different unitary conductances. Apparently there is significant channel-to-channel variation at a site in the outer pore or in the selectivity filter, leading to variability in the rate at which K(+) or Cs(+) enters the channel.
Abrams,
The role of a single aspartate residue in ionic selectivity and block of a murine inward rectifier K+ channel Kir2.1.
1996, Pubmed
Abrams,
The role of a single aspartate residue in ionic selectivity and block of a murine inward rectifier K+ channel Kir2.1.
1996,
Pubmed Anderson,
Voltage clamp analysis of acetylcholine produced end-plate current fluctuations at frog neuromuscular junction.
1973,
Pubmed Biermans,
The mechanism of the inactivation of the inward-rectifying K current during hyperpolarizing steps in guinea-pig ventricular myocytes.
1987,
Pubmed Colquhoun,
Relaxation and fluctuations of membrane currents that flow through drug-operated channels.
1977,
Pubmed Conti,
Channel noise in nerve membranes and lipid bilayers.
1975,
Pubmed Cull-Candy,
Multiple-conductance channels activated by excitatory amino acids in cerebellar neurons.
,
Pubmed Doyle,
The structure of the potassium channel: molecular basis of K+ conduction and selectivity.
1998,
Pubmed Elam,
The role of Mg2+ in the inactivation of inwardly rectifying K+ channels in aortic endothelial cells.
1995,
Pubmed Fox,
Ion channel subconductance states.
1987,
Pubmed Hamill,
Activation of multiple-conductance state chloride channels in spinal neurones by glycine and GABA.
,
Pubmed Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed Hedin,
Cloning of a Xenopus laevis inwardly rectifying K+ channel subunit that permits GIRK1 expression of IKACh currents in oocytes.
1996,
Pubmed
,
Xenbase Hunter,
Multi-barrelled K channels in renal tubules.
,
Pubmed Isenberg,
Cardiac Purkinje fibers: cesium as a tool to block inward rectifying potassium currents.
1976,
Pubmed Ishihara,
Gating mechanism of the cloned inward rectifier potassium channel from mouse heart.
1994,
Pubmed
,
Xenbase Jahr,
Glutamate activates multiple single channel conductances in hippocampal neurons.
,
Pubmed Josephson,
Inwardly rectifying single-channel and whole cell K+ currents in rat ventricular myocytes.
1986,
Pubmed Kameyama,
Single channel analysis of the inward rectifier K current in the rabbit ventricular cells.
1983,
Pubmed Katz,
The statistical nature of the acetycholine potential and its molecular components.
1972,
Pubmed Kazachenko,
The potential-dependent K+ channel in molluscan neurones is organized in a cluster of elementary channels.
1984,
Pubmed Krouse,
A large anion-selective channel has seven conductance levels.
,
Pubmed Kubo,
Primary structure and functional expression of a mouse inward rectifier potassium channel.
1993,
Pubmed
,
Xenbase Lopatin,
[K+] dependence of open-channel conductance in cloned inward rectifier potassium channels (IRK1, Kir2.1).
1996,
Pubmed
,
Xenbase Lu,
Architecture of a K+ channel inner pore revealed by stoichiometric covalent modification.
1999,
Pubmed
,
Xenbase Matsuda,
Single inwardly rectifying potassium channels in cultured muscle cells from rat and mouse.
1989,
Pubmed Matsuda,
Open-state substructure of inwardly rectifying potassium channels revealed by magnesium block in guinea-pig heart cells.
1988,
Pubmed Matsuda,
Triple-barrel structure of inwardly rectifying K+ channels revealed by Cs+ and Rb+ block in guinea-pig heart cells.
1989,
Pubmed Methfessel,
Patch clamp measurements on Xenopus laevis oocytes: currents through endogenous channels and implanted acetylcholine receptor and sodium channels.
1986,
Pubmed
,
Xenbase Miller,
Open-state substructure of single chloride channels from Torpedo electroplax.
1982,
Pubmed Nakamura,
Inhibition of rat ventricular IK1 with antisense oligonucleotides targeted to Kir2.1 mRNA.
1998,
Pubmed
,
Xenbase Neher,
The extracellular patch clamp: a method for resolving currents through individual open channels in biological membranes.
1978,
Pubmed Neher,
Conductance fluctuations and ionic pores in membranes.
1977,
Pubmed Nichols,
Inward rectifier potassium channels.
1997,
Pubmed Patlak,
Measuring kinetics of complex single ion channel data using mean-variance histograms.
1993,
Pubmed Payet,
Single-channel analysis of a potassium inward rectifier in myocytes of newborn rat heart.
1985,
Pubmed Plaster,
Mutations in Kir2.1 cause the developmental and episodic electrical phenotypes of Andersen's syndrome.
2001,
Pubmed
,
Xenbase Rae,
Inwardly rectifying potassium channels in lens epithelium are from the IRK1 (Kir 2.1) family.
1998,
Pubmed Recio-Pinto,
Neuraminidase treatment modifies the function of electroplax sodium channels in planar lipid bilayers.
1990,
Pubmed Sakmann,
Voltage-dependent inactivation of inward-rectifying single-channel currents in the guinea-pig heart cell membrane.
1984,
Pubmed Sakmann,
Conductance properties of single inwardly rectifying potassium channels in ventricular cells from guinea-pig heart.
1984,
Pubmed Stampe,
Nonindependent K+ movement through the pore in IRK1 potassium channels.
1998,
Pubmed
,
Xenbase Takahashi,
Molecular cloning and functional expression of cDNA encoding a second class of inward rectifier potassium channels in the mouse brain.
1994,
Pubmed
,
Xenbase Thompson,
Residues beyond the selectivity filter of the K+ channel kir2.1 regulate permeation and block by external Rb+ and Cs+.
2000,
Pubmed Tinker,
Regions responsible for the assembly of inwardly rectifying potassium channels.
1996,
Pubmed
,
Xenbase Zhu,
Identification of endogenous outward currents in the human embryonic kidney (HEK 293) cell line.
1998,
Pubmed
