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Transport of Gibberellin A1 in Cowpea Membrane Vesicles

Transport of Gibberellin A1 in Cowpea Membrane Vesicles Abstract The permeability properties of gibberellin A1 (GA1) were examined in membrane vesicles isolated from cowpea hypocotyls. The rate of GA1 uptake was progressively greater as pH decreased, indicating that the neutral molecule is more permeable than anionic GA1. Membrane vesicles used in this study possessed a tonoplast-type H+-translocating ATPase as assayed by MgATP-dependent quenching of acridine orange fluorescence and methylamine uptake. However, GA1 uptake was not stimulated by MgATP. At concentrations in excess of 1 micromolar, GA1, GA5, and GA, collapsed both MgATP-generated and artifically imposed pH gradients, apparently by shuttling H+ across the membrane as neutral GA. The relatively high permeability of neutral GA and the potentially detrimental effects of GA in uncoupling pH gradients across intracellular membranes supports the view that GA1 accumulation and compartmentation must occur by conversion of GA1 to more polar metabolites. 2 Present address: Department of Genetics, Briggs Hall, University of California, Davis, CA 95616. 1 Supported by National Science Foundation grant NSF-PCM81-14942. This content is only available as a PDF. © 1986 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model) http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png PLANT PHYSIOLOGY Oxford University Press

Transport of Gibberellin A1 in Cowpea Membrane Vesicles

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References (25)

Publisher
Oxford University Press
Copyright
Copyright © 2021 American Society of Plant Biologists
ISSN
0032-0889
eISSN
1532-2548
DOI
10.1104/pp.80.4.812
Publisher site
See Article on Publisher Site

Abstract

Abstract The permeability properties of gibberellin A1 (GA1) were examined in membrane vesicles isolated from cowpea hypocotyls. The rate of GA1 uptake was progressively greater as pH decreased, indicating that the neutral molecule is more permeable than anionic GA1. Membrane vesicles used in this study possessed a tonoplast-type H+-translocating ATPase as assayed by MgATP-dependent quenching of acridine orange fluorescence and methylamine uptake. However, GA1 uptake was not stimulated by MgATP. At concentrations in excess of 1 micromolar, GA1, GA5, and GA, collapsed both MgATP-generated and artifically imposed pH gradients, apparently by shuttling H+ across the membrane as neutral GA. The relatively high permeability of neutral GA and the potentially detrimental effects of GA in uncoupling pH gradients across intracellular membranes supports the view that GA1 accumulation and compartmentation must occur by conversion of GA1 to more polar metabolites. 2 Present address: Department of Genetics, Briggs Hall, University of California, Davis, CA 95616. 1 Supported by National Science Foundation grant NSF-PCM81-14942. This content is only available as a PDF. © 1986 American Society of Plant Biologists This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/open_access/funder_policies/chorus/standard_publication_model)

Journal

PLANT PHYSIOLOGYOxford University Press

Published: Apr 1, 1986

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