Permeation of Ca2+ and monovalent cations through an outwardly rectifying channel in maize root stelar cells

Biomedical and Life Sciences

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https://doi.org/10.1093/jxb/48.4.839
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Keywords

maize roots, K+ channel selectivity, Ca2+ permeation, PATCH CLAMP EXPERIMENTS, PLANAR LIPID BILAYERS, FABA GUARD-CELLS, PLASMA-MEMBRANE, ION CHANNELS, POTASSIUM CHANNELS, K+ CHANNELS, RYE ROOTS, PROTOPLASTS, SELECTIVITY

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Permeation of Ca2+ and monovalent cations through an outwardly rectifying channel in maize root stelar cells. / Roberts, Stephen K.; Tester, Mark.
In: Journal of Experimental Botany, Vol. 48, No. 309, 04.1997, p. 839-846.

Research output: Contribution to Journal/Magazine › Journal article › peer-review

Bibtex

@article{6644aa27a9d045a7b852d5295e719ac8,

title = "Permeation of Ca2+ and monovalent cations through an outwardly rectifying channel in maize root stelar cells",

abstract = "A depolarization-activated outwardly-rectifying channel (OR), most likely involved in the passive release of K+ from the root symplasm into the stelar apoplast (for subsequent transport to the shoot via the xylem vessels), has been characterized in the plasma membrane of maize root stelar cells (Roberts and Tester, 1995), In the present study, the selectivity of this channel was further characterized using single channel current-voltage curves generated using a voltage ramp protocol. This protocol permitted the accurate and unambiguous measurement of the reversal potentials of currents resulting from single channel openings, Using the voltage ramp protocol, it was shown that the OR allows both K+ efflux and Ca2+ influx at potentials positive of E-K and negative of E-Ca, The OR had a P-Ca/P-K of 1.72-0.21 decreasing as extracellular Ca2+ was increased, The permeability of the OR for monovalent cations other than K+ was also investigated. In bi-ionic conditions, a relative permeability sequence of K+ greater than or equal to Rb+ > Cs+ > Na+ = NH4+ was determined Eisenman sequence IV), The physiological implications of the selectivity of the OR are discussed.",

keywords = "maize roots, K+ channel selectivity, Ca2+ permeation, PATCH CLAMP EXPERIMENTS, PLANAR LIPID BILAYERS, FABA GUARD-CELLS, PLASMA-MEMBRANE, ION CHANNELS, POTASSIUM CHANNELS, K+ CHANNELS, RYE ROOTS, PROTOPLASTS, SELECTIVITY",

author = "Roberts, {Stephen K.} and Mark Tester",

year = "1997",

month = apr,

doi = "10.1093/jxb/48.4.839",

language = "English",

volume = "48",

pages = "839--846",

journal = "Journal of Experimental Botany",

issn = "0022-0957",

publisher = "OXFORD UNIV PRESS",

number = "309",

}

RIS

TY - JOUR

T1 - Permeation of Ca2+ and monovalent cations through an outwardly rectifying channel in maize root stelar cells

AU - Roberts, Stephen K.

AU - Tester, Mark

PY - 1997/4

Y1 - 1997/4

N2 - A depolarization-activated outwardly-rectifying channel (OR), most likely involved in the passive release of K+ from the root symplasm into the stelar apoplast (for subsequent transport to the shoot via the xylem vessels), has been characterized in the plasma membrane of maize root stelar cells (Roberts and Tester, 1995), In the present study, the selectivity of this channel was further characterized using single channel current-voltage curves generated using a voltage ramp protocol. This protocol permitted the accurate and unambiguous measurement of the reversal potentials of currents resulting from single channel openings, Using the voltage ramp protocol, it was shown that the OR allows both K+ efflux and Ca2+ influx at potentials positive of E-K and negative of E-Ca, The OR had a P-Ca/P-K of 1.72-0.21 decreasing as extracellular Ca2+ was increased, The permeability of the OR for monovalent cations other than K+ was also investigated. In bi-ionic conditions, a relative permeability sequence of K+ greater than or equal to Rb+ > Cs+ > Na+ = NH4+ was determined Eisenman sequence IV), The physiological implications of the selectivity of the OR are discussed.

AB - A depolarization-activated outwardly-rectifying channel (OR), most likely involved in the passive release of K+ from the root symplasm into the stelar apoplast (for subsequent transport to the shoot via the xylem vessels), has been characterized in the plasma membrane of maize root stelar cells (Roberts and Tester, 1995), In the present study, the selectivity of this channel was further characterized using single channel current-voltage curves generated using a voltage ramp protocol. This protocol permitted the accurate and unambiguous measurement of the reversal potentials of currents resulting from single channel openings, Using the voltage ramp protocol, it was shown that the OR allows both K+ efflux and Ca2+ influx at potentials positive of E-K and negative of E-Ca, The OR had a P-Ca/P-K of 1.72-0.21 decreasing as extracellular Ca2+ was increased, The permeability of the OR for monovalent cations other than K+ was also investigated. In bi-ionic conditions, a relative permeability sequence of K+ greater than or equal to Rb+ > Cs+ > Na+ = NH4+ was determined Eisenman sequence IV), The physiological implications of the selectivity of the OR are discussed.

KW - maize roots

KW - K+ channel selectivity

KW - Ca2+ permeation

KW - PATCH CLAMP EXPERIMENTS

KW - PLANAR LIPID BILAYERS

KW - FABA GUARD-CELLS

KW - PLASMA-MEMBRANE

KW - ION CHANNELS

KW - POTASSIUM CHANNELS

KW - K+ CHANNELS

KW - RYE ROOTS

KW - PROTOPLASTS

KW - SELECTIVITY

U2 - 10.1093/jxb/48.4.839

DO - 10.1093/jxb/48.4.839

M3 - Journal article

VL - 48

SP - 839

EP - 846

JO - Journal of Experimental Botany

JF - Journal of Experimental Botany

SN - 0022-0957

IS - 309

ER -

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