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.
Expression and permeation properties of the K(+) channel Kir7.1 in the retinal pigment epithelium.
Shimura M
,
Yuan Y
,
Chang JT
,
Zhang S
,
Campochiaro PA
,
Zack DJ
,
Hughes BA
.
???displayArticle.abstract???
Bovine Kir7.1 clones were obtained from a retinal pigment epithelium (RPE)-subtracted cDNA library. Human RPE cDNA library screening resulted in clones encoding full-length human Kir7.1. Northern blot analysis indicated that bovine Kir7.1 is highly expressed in the RPE. Human Kir7.1 channels were expressed in Xenopus oocytes and studied using the two-electrode voltage-clamp technique. The macroscopic Kir7.1 conductance exhibited mild inward rectification and an inverse dependence on extracellular K+ concentration ([K+]o). The selectivity sequence based on permeability ratios was K+ (1.0) approximately Rb+ (0.89) > Cs+ (0.013) > Na+ (0.003) approximately Li+ (0.001) and the sequence based on conductance ratios was Rb+ (9.5) > K+ (1.0) > Na+ (0.458) > Cs+ (0.331) > Li+ (0.139). Non-stationary noise analysis of Rb+ currents in cell-attached patches yielded a unitary conductance for Kir7.1 of approximately 2 pS. In whole-cell recordings from freshly isolated bovine RPE cells, the predominant current was a mild inwardly rectifying K+ current that exhibited an inverse dependence of conductance on [K+]o. The selectivity sequence based on permeability ratios was K+ (1.0) approximately Rb+ (0.89) > Cs+ (0.021) > Na+ (0.003) approximately Li+ (0.002) and the sequence based on conductance ratios was Rb+ (8.9) > K+ (1.0) > Na+ (0.59) > Cs+ (0.23) > Li+ (0.08). In cell-attached recordings with Rb+ in the pipette, inwardly rectifying currents were observed in nine of 12 patches of RPE apical membrane but in only one of 13 basolateral membrane patches. Non-stationary noise analysis of Rb+ currents in cell-attached apical membrane patches yielded a unitary conductance for RPE Kir of approximately 2 pS. On the basis of this molecular and electrophysiological evidence, we conclude that Kir7.1 channel subunits comprise the K+ conductance of the RPE apical membrane.
Baumgartner,
Two-microelectrode voltage clamp of Xenopus oocytes: voltage errors and compensation for local current flow.
1999, Pubmed,
Xenbase
Baumgartner,
Two-microelectrode voltage clamp of Xenopus oocytes: voltage errors and compensation for local current flow.
1999,
Pubmed
,
Xenbase
Bialek,
K+ and Cl- transport mechanisms in bovine pigment epithelium that could modulate subretinal space volume and composition.
1994,
Pubmed
Chang,
Cloning and characterization of a secreted frizzled-related protein that is expressed by the retinal pigment epithelium.
1999,
Pubmed
,
Xenbase
Chang,
Mammalian homolog of Drosophila retinal degeneration B rescues the mutant fly phenotype.
1997,
Pubmed
Choe,
Permeation and gating of an inwardly rectifying potassium channel. Evidence for a variable energy well.
1998,
Pubmed
,
Xenbase
Döring,
The epithelial inward rectifier channel Kir7.1 displays unusual K+ permeation properties.
1998,
Pubmed
,
Xenbase
Goldin,
Maintenance of Xenopus laevis and oocyte injection.
1992,
Pubmed
,
Xenbase
Griff,
Ba2+ unmasks K+ modulation of the Na+-K+ pump in the frog retinal pigment epithelium.
1985,
Pubmed
Hamill,
Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches.
1981,
Pubmed
Heinemann,
Nonstationary noise analysis and application to patch clamp recordings.
1992,
Pubmed
Ho,
Cloning and expression of an inwardly rectifying ATP-regulated potassium channel.
1993,
Pubmed
,
Xenbase
Huang,
Light-evoked expansion of subretinal space volume in the retina of the frog.
1992,
Pubmed
Hughes,
Apical electrogenic NaHCO3 cotransport. A mechanism for HCO3 absorption across the retinal pigment epithelium.
1989,
Pubmed
Hughes,
Voltage-dependent currents in isolated cells of the frog retinal pigment epithelium.
1990,
Pubmed
Hughes,
Effects of Ba2+ and Cs+ on apical membrane K+ conductance in toad retinal pigment epithelium.
1995,
Pubmed
Hughes,
ATP-dependent regulation of inwardly rectifying K+ current in bovine retinal pigment epithelial cells.
1998,
Pubmed
Hughes,
An outwardly rectifying K+ current active near resting potential in human retinal pigment epithelial cells.
1995,
Pubmed
Hughes,
Inwardly rectifying K+ currents in isolated human retinal pigment epithelial cells.
1996,
Pubmed
Jackson,
Single channel properties of a volume sensitive anion channel: lessons from noise analysis.
1996,
Pubmed
Joseph,
Apical and basal membrane ion transport mechanisms in bovine retinal pigment epithelium.
1991,
Pubmed
Kofuji,
Evidence that neuronal G-protein-gated inwardly rectifying K+ channels are activated by G beta gamma subunits and function as heteromultimers.
1995,
Pubmed
,
Xenbase
Krapivinsky,
A novel inward rectifier K+ channel with unique pore properties.
1998,
Pubmed
Kubo,
Primary structure and functional expression of a mouse inward rectifier potassium channel.
1993,
Pubmed
,
Xenbase
Kusaka,
Expression and polarized distribution of an inwardly rectifying K+ channel, Kir4.1, in rat retinal pigment epithelium.
1999,
Pubmed
Lasansky,
Potential, current, and ionic fluxes across the isolated retinal pigment epithelium and choriod.
1966,
Pubmed
Li,
Light-dependent hydration of the space surrounding photoreceptors in chick retina.
1994,
Pubmed
Löffler,
Cation permeation and blockade of ROMK1, a cloned renal potassium channel.
1997,
Pubmed
,
Xenbase
Lopatin,
[K+] dependence of open-channel conductance in cloned inward rectifier potassium channels (IRK1, Kir2.1).
1996,
Pubmed
,
Xenbase
Miller,
Passive ionic properties of frog retinal pigment epithelium.
1977,
Pubmed
Miller,
Potassium transport across the frog retinal pigment epithelium.
1982,
Pubmed
Miller,
Active ion transport pathways in the bovine retinal pigment epithelium.
1990,
Pubmed
Miller,
The electrogenic sodium pump of the frog retinal pigment epithelium.
1978,
Pubmed
Nakamura,
Inwardly rectifying K+ channel Kir7.1 is highly expressed in thyroid follicular cells, intestinal epithelial cells and choroid plexus epithelial cells: implication for a functional coupling with Na+,K+-ATPase.
1999,
Pubmed
Nakamura,
Complex structure and regulation of expression of the rat gene for inward rectifier potassium channel Kir7.1.
2000,
Pubmed
Nichols,
Inward rectifier potassium channels.
1997,
Pubmed
Oakley,
Correlation of light-induced changes in retinal extracellular potassium concentration with c-wave of the electroretinogram.
1976,
Pubmed
Okami,
Immunocytochemical localization of Na+,K(+)-ATPase in rat retinal pigment epithelial cells.
1990,
Pubmed
Partiseti,
Cloning and characterization of a novel human inwardly rectifying potassium channel predominantly expressed in small intestine.
1998,
Pubmed
,
Xenbase
Quinn,
Ion transport mechanisms in native human retinal pigment epithelium.
1992,
Pubmed
Reimann,
Inwardly rectifying potassium channels.
1999,
Pubmed
Reuveny,
Contributions of a negatively charged residue in the hydrophobic domain of the IRK1 inwardly rectifying K+ channel to K(+)-selective permeation.
1996,
Pubmed
,
Xenbase
Rodriguez-Boulan,
Polarity signals in epithelial cells.
1993,
Pubmed
Segawa,
Properties of the inwardly rectifying K+ conductance in the toad retinal pigment epithelium.
1994,
Pubmed
Shuck,
Cloning and characterization of two K+ inward rectifier (Kir) 1.1 potassium channel homologs from human kidney (Kir1.2 and Kir1.3).
1997,
Pubmed
,
Xenbase
Standen,
Rubidium block and rubidium permeability of the inward rectifier of frog skeletal muscle fibres.
1980,
Pubmed
Steinberg,
Aspects of electrolyte transport in frog pigment epithelium.
1973,
Pubmed
Stühmer,
Electrophysiological recording from Xenopus oocytes.
1992,
Pubmed
,
Xenbase
Takahira,
Isolated bovine retinal pigment epithelial cells express delayed rectifier type and M-type K+ currents.
1997,
Pubmed
Takumi,
A novel ATP-dependent inward rectifier potassium channel expressed predominantly in glial cells.
1995,
Pubmed
,
Xenbase
Traynelis,
Getting the most out of noise in the central nervous system.
1998,
Pubmed
Welling,
Primary structure and functional expression of a cortical collecting duct Kir channel.
1997,
Pubmed
,
Xenbase
Wischmeyer,
Stable cation coordination at a single outer pore residue defines permeation properties in Kir channels.
2000,
Pubmed
,
Xenbase
Zhou,
Primary structure and functional properties of an epithelial K channel.
1994,
Pubmed
,
Xenbase
