Related Experiment Video
Updated: Jun 12, 2026

Measuring Fluxes of Mineral Nutrients and Toxicants in Plants with Radioactive Tracers
Published on: August 22, 2014
Characterization of an intact two-component high-affinity nitrate transporter from Arabidopsis roots
Zhenhua Yong1, Zorica Kotur, Anthony D M Glass
1Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada.
Abstract:
AtNRT2.1, a polypeptide of the Arabidopsis thaliana two-component inducible high-affinity nitrate transport system (IHATS), is located within the plasma membrane. The monomeric form of AtNRT2.1 has been reported to be the most abundant form, and was suggested to be the form that is active in nitrate transport. Here we have used immunological and transient protoplast expression methods to demonstrate that an intact two-component complex of AtNRT2.1 and AtNAR2.1 (AtNRT3.1) is localized in the plasma membrane. A. thaliana mutants lacking AtNAR2.1 have virtually no IHATS capacity and exhibit extremely poor growth on low nitrate as the sole source of nitrogen. Near-normal growth and nitrate transport in the mutant were restored by transformation with myc-tagged AtNAR2.1 cDNA. Membrane fractions from roots of the restored myc-tagged line were solubilized in 1.5% dodecyl-β-maltoside and partially purified in the first dimension by blue native gel electrophoresis. Using anti-NRT2.1 antibodies, an oligomeric polypeptide (approximate molecular mass 150 kDa) was identified, but monomeric AtNRT2.1 was absent. This oligomer was also observed in the wild-type, and was resolved, using SDS-PAGE for the second dimension, into two polypeptides with molecular masses of approximately 48 and 26 kDa, corresponding to AtNRT2.1 and myc-tagged AtNAR2.1, respectively. This result, together with the finding that the oligomer is absent from NRT2.1 or NAR2.1 mutants, suggests that this complex, rather than monomeric AtNRT2.1, is the form that is active in IHATS nitrate transport. The molecular mass of the intact oligomer suggests that the functional unit for high-affinity nitrate influx may be a tetramer consisting of two subunits each of AtNRT2.1 and AtNAR2.1.
More Related Videos
09:41Translating Ribosome Affinity Purification (TRAP) to Investigate Arabidopsis thaliana Root Development at a Cell Type-Specific Scale
Published on: May 14, 2020
13:16Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
Published on: December 31, 2019
Related Concept Videos
Water and Mineral Acquisition
Short-distance Transport of Resources
Inorganic Nitrogen Assimilation
Protein Transport to the Inner Chloroplast Membrane
ABC Transporters: Exporter
The Significance of Membrane Transport
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...