Related Experiment Video
Updated: Sep 25, 2026

Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers
Published on: August 22, 2014
Nitrate transport across the tonoplast of Cucumis sativus L. root cells
Katarzyna Kabała1, Grazyna Kłobus, Małgorzata Janicka-Russak
1Plant Physiology Department, Institute of Botany, Wrocław University, Kanonia 6/8, 50-328 Wrocław, Poland.
Abstract:
Nitrate transport across the tonoplast has been studied using vacuole membranes isolated from cucumber roots grown in nitrate. The addition of NO3- ions into the tonoplast with ATP-generated transmembrane proton gradient caused the dissipation of delta pH, indicating the NO3(-)-induced proton efflux from vesicles. NO3(-)-dependent H+ efflux was almost insensitive to the transmembrane electrical potential difference, suggesting the presence of an electroneutral NO3-/H+ antiporter in the tonoplast. Apart from saturation kinetics, with respect to nitrate ions, NO3(-)-linked H+ efflux from the tonoplast of cucumber roots showed other characteristics expected of substrate-specific transporters. Experiments employing protein modifying reagents (NEM, pCMBS, PGO and SITS) indicated that a crucial role in the activity of tonoplast nitrate/proton antiporter is played by lysine residues (strong inhibition of NO3-/H+ antiport by SITS). None of the ion-channel inhibitors (NIF, ZnSO4 and TEA-Cl) used in the experiments had a direct effect on the nitrate transport into tonoplast membranes. On the other hand, every protein reagent, as well as NIF and ZnSO4, significantly affected the ATP-dependent proton transport in vesicles. Only TEA-Cl, the potassium channel blocker, had no effect on the vacuolar proton pumping activity.
More Related Videos
13:16Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
08:31Agrobacterium tumefaciens and Agrobacterium rhizogenes-Mediated Transformation of Potato and the Promoter Activity of a Suberin Gene by GUS Staining
Published on: March 29, 2019
Related Concept Videos
Short-distance Transport of Resources
Water and Mineral Acquisition
The Apoplast and Symplast
Transcellular Transport of Solutes
Key Elements for Plant Nutrition
Protein Transport to the Inner Chloroplast Membrane