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Updated: Aug 31, 2025

Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Picrotoxin Delineates Different Transport Configurations for Malate and γ Aminobutyric Acid through TaALMT1
Sunita A Ramesh1,2, Yu Long2,3, Abolfazl Dashtbani-Roozbehani1
1Biological Sciences, College of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia.
Abstract:
Plant-derived pharmacological agents have been used extensively to dissect the structure-function relationships of mammalian GABA receptors and ion channels. Picrotoxin is a non-competitive antagonist of mammalian GABAA receptors. Here, we report that picrotoxin inhibits the anion (malate) efflux mediated by wheat (Triticum aestivum) ALMT1 but has no effect on GABA transport. The EC50 for inhibition was 0.14 nM and 0.18 nM when the ALMTs were expressed in tobacco BY2 cells and in Xenopus oocytes, respectively. Patch clamping of the oocyte plasma membrane expressing wheat ALMT1 showed that picrotoxin inhibited malate currents from both sides of the membrane. These results demonstrate that picrotoxin inhibits anion efflux effectively and can be used as a new inhibitor to study the ion fluxes mediated by ALMT proteins that allow either GABA or anion transport.
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