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Ion channels in Arabidopsis plasma membrane : transport characteristics and involvement in light-induced voltage changes.

Spalding, E. P. and Slayman, C. L. and Goldsmith, M. H. M. and Gradmann, D. and Bertl, A. (1992):
Ion channels in Arabidopsis plasma membrane : transport characteristics and involvement in light-induced voltage changes.
99, In: Plant physiology, (1), pp. 96-102, ISSN 0032-0889, [Online-Edition: http://www.plantphysiol.org/cgi/reprint/99/1/96],
[Article]

Abstract

White light (25 watts per square meter) induced an increase in plasma membrane K(+)-channel activity and a 30- to 70-millivolt transient membrane depolarization (completed in 2-3 minutes) in Arabidopsis thaliana leaf mesophyll cells. Transport characteristics of three types of ion channels in the plasma membrane were determined using inside-out patches. With 220 millimolar K(+) on the cytoplasmic side of the patch and 50 millimolar K(+) in the pipette, (220/50 K), the open-channel current-voltage curves of these channels were sigmoidal and consistent with an enzyme kinetic model. Two channel types were selective for K(+) over Na(+) and Cl(-). One (named PKC1) had a maximum conductance (G(max)) of 44 picosiemens at a membrane voltage (V(m)) of -65 mV in (220/50 K) and is stimulated by light. The other (PKC2) had G(max) = 66 picosiemens at V(m) = 60 millivolts in (220/50 K). The third channel type (PCC1) transported K(+) and Na(+) about equally well but not Cl(-). It had G(max) = 109 picosiemens at V(m) = 55 millivolts in (250/50 K) with 10 millimolar Ca(2+) on the cytoplasmic side. Reducing Ca(2+) to 0.1 millimolar increased PCC1 open-channel currents by approximately 50% in a voltage-independent manner. Averaged over time, PKC2 and PCC1 currents strongly outward rectified and PKC1 currents did so weakly. Reductants (1 millimolar dithiothreitol or 10 millimolar beta-mercaptoethanol) added to the cytoplasmic side of an excised patch increased the open probability of all three channel types.

Item Type: Article
Erschienen: 1992
Creators: Spalding, E. P. and Slayman, C. L. and Goldsmith, M. H. M. and Gradmann, D. and Bertl, A.
Title: Ion channels in Arabidopsis plasma membrane : transport characteristics and involvement in light-induced voltage changes.
Language: English
Abstract:

White light (25 watts per square meter) induced an increase in plasma membrane K(+)-channel activity and a 30- to 70-millivolt transient membrane depolarization (completed in 2-3 minutes) in Arabidopsis thaliana leaf mesophyll cells. Transport characteristics of three types of ion channels in the plasma membrane were determined using inside-out patches. With 220 millimolar K(+) on the cytoplasmic side of the patch and 50 millimolar K(+) in the pipette, (220/50 K), the open-channel current-voltage curves of these channels were sigmoidal and consistent with an enzyme kinetic model. Two channel types were selective for K(+) over Na(+) and Cl(-). One (named PKC1) had a maximum conductance (G(max)) of 44 picosiemens at a membrane voltage (V(m)) of -65 mV in (220/50 K) and is stimulated by light. The other (PKC2) had G(max) = 66 picosiemens at V(m) = 60 millivolts in (220/50 K). The third channel type (PCC1) transported K(+) and Na(+) about equally well but not Cl(-). It had G(max) = 109 picosiemens at V(m) = 55 millivolts in (250/50 K) with 10 millimolar Ca(2+) on the cytoplasmic side. Reducing Ca(2+) to 0.1 millimolar increased PCC1 open-channel currents by approximately 50% in a voltage-independent manner. Averaged over time, PKC2 and PCC1 currents strongly outward rectified and PKC1 currents did so weakly. Reductants (1 millimolar dithiothreitol or 10 millimolar beta-mercaptoethanol) added to the cytoplasmic side of an excised patch increased the open probability of all three channel types.

Journal or Publication Title: Plant physiology
Volume: 99
Number: 1
Divisions: 10 Department of Biology
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10 Department of Biology > Yeast Membrane Biology
Date Deposited: 25 Nov 2010 15:26
Official URL: http://www.plantphysiol.org/cgi/reprint/99/1/96
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