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Proc Natl Acad Sci U S A
1999 Jun 22;9613:7581-6. doi: 10.1073/pnas.96.13.7581.
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AKT3, a phloem-localized K+ channel, is blocked by protons.
Marten I
,
Hoth S
,
Deeken R
,
Ache P
,
Ketchum KA
,
Hoshi T
,
Hedrich R
.
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The potassium-channel gene, AKT3, has recently been isolated from an Arabidopsis thaliana cDNA library. By using the whole-mount and in situ hybridization techniques, we found AKT3 predominantly expressed in the phloem. To study the physiological role of this channel type, AKT3 was heterologously expressed in Xenopus oocytes, and the electrical properties were examined with voltage-clamp techniques. Unlike the plant inward-rectifying guard cell K+ channels KAT1 and KST1, the AKT3 channels were only weakly regulated by the membrane potential. Furthermore, AKT3 was blocked by physiological concentrations of external Ca2+ and showed an inverted pH regulation. Extracellular acidification decreased the macroscopic AKT3 currents by reducing the single-channel conductance. Because assimilate transport in the vascular tissue coincides with both H+ and K+ fluxes, AKT3 K+ channels may be involved in K+ transport accompanying phloem loading and unloading processes.
Baizabal-Aguirre,
Suppression of inward-rectifying K+ channels KAT1 and AKT2 by dominant negative point mutations in the KAT1 alpha-subunit.
1999, Pubmed
Baizabal-Aguirre,
Suppression of inward-rectifying K+ channels KAT1 and AKT2 by dominant negative point mutations in the KAT1 alpha-subunit.
1999,
Pubmed
Becker,
Changes in voltage activation, Cs+ sensitivity, and ion permeability in H5 mutants of the plant K+ channel KAT1.
1996,
Pubmed
,
Xenbase
Blatt,
K+ channels of stomatal guard cells. Characteristics of the inward rectifier and its control by pH.
1992,
Pubmed
Brüggemann,
Pronounced differences between the native K+ channels and KAT1 and KST1 alpha-subunit homomers of guard cells.
1999,
Pubmed
,
Xenbase
Cao,
Multiple genes, tissue specificity, and expression-dependent modulationcontribute to the functional diversity of potassium channels in Arabidopsis thaliana.
1995,
Pubmed
,
Xenbase
Dreyer,
Single mutations strongly alter the K+-selective pore of the K(in) channel KAT1.
1998,
Pubmed
,
Xenbase
Dreyer,
Plant K+ channel alpha-subunits assemble indiscriminately.
1997,
Pubmed
,
Xenbase
Fairley-Grenot,
Permeation of Ca2+ through K+ channels in the plasma membrane of Vicia faba guard cells.
1992,
Pubmed
Gaymard,
Identification and disruption of a plant shaker-like outward channel involved in K+ release into the xylem sap.
1998,
Pubmed
,
Xenbase
Gaymard,
The baculovirus/insect cell system as an alternative to Xenopus oocytes. First characterization of the AKT1 K+ channel from Arabidopsis thaliana.
1996,
Pubmed
,
Xenbase
Hedrich,
Inward rectifier potassium channels in plants differ from their animal counterparts in response to voltage and channel modulators.
1995,
Pubmed
,
Xenbase
Hoshi,
Regulation of voltage dependence of the KAT1 channel by intracellular factors.
1995,
Pubmed
,
Xenbase
Hoth,
Molecular basis of plant-specific acid activation of K+ uptake channels.
1997,
Pubmed
,
Xenbase
Hoth,
Distinct molecular bases for pH sensitivity of the guard cell K+ channels KST1 and KAT1.
1999,
Pubmed
,
Xenbase
Ilan,
External protons enhance the activity of the hyperpolarization-activated K channels in guard cell protoplasts of Vicia faba.
1996,
Pubmed
Ketchum,
Isolation of an ion channel gene from Arabidopsis thaliana using the H5 signature sequence from voltage-dependent K+ channels.
1996,
Pubmed
,
Xenbase
Kinraide,
A Quantitative Simulation Model for H-Amino Acid Cotransport To Interpret the Effects of Amino Acids on Membrane Potential and Extracellular pH.
1984,
Pubmed
Mengel,
Effect of Potassium Supply on the Rate of Phloem Sap Exudation and the Composition of Phloem Sap of Ricinus communis.
1977,
Pubmed
Müller-Röber,
Cloning and electrophysiological analysis of KST1, an inward rectifying K+ channel expressed in potato guard cells.
1995,
Pubmed
,
Xenbase
Roelfsema,
The membrane potential of Arabidopsis thaliana guard cells; depolarizations induced by apoplastic acidification.
1998,
Pubmed
Schachtman,
Expression of an inward-rectifying potassium channel by the Arabidopsis KAT1 cDNA.
1992,
Pubmed
,
Xenbase
Thiel,
Small inward rectifying K+ channels in coleoptiles: inhibition by external Ca2+ and function in cell elongation.
1996,
Pubmed
Uozumi,
Determination of transmembrane topology of an inward-rectifying potassium channel from Arabidopsis thaliana based on functional expression in Escherichia coli.
1998,
Pubmed
Wegner,
Properties of the K+ inward rectifier in the plasma membrane of xylem parenchyma cells from barley roots: effects of TEA+, Ca2+, Ba2+ and La3+.
1994,
Pubmed
Wegner,
Ion Channels in the Xylem Parenchyma of Barley Roots (A Procedure to Isolate Protoplasts from This Tissue and a Patch-Clamp Exploration of Salt Passageways into Xylem Vessels.
1994,
Pubmed
Woodhull,
Ionic blockage of sodium channels in nerve.
1973,
Pubmed
Zimmermann,
Characterization of SKT1, an inwardly rectifying potassium channel from potato, by heterologous expression in insect cells.
1998,
Pubmed
