biostudies-literatureUnknown11Hao DLAtAMT1;3 is a major contributor to high-affinity ammonium uptake in <i>Arabidopsis</i> roots. Using a stable electrophysiological recording strategy, we demonstrate in <i>Xenopus laevis</i> oocytes that AtAMT1;3 functions as a typical high-affinity NH₄ ⁺ uniporter independent of protons and Ca²⁺. The findings that AtAMT1;3 transports methylammonium (MeA⁺, a chemical analog of NH₄ ⁺) with extremely low affinity (<i>K</i> _m in the range of 2.9-6.1 mM) led to investigate the mechanisms underlying substrate binding. Homologous modeling and substrate docking analyses predicted that the deduced substrate binding motif of AtAMT1;3 facilitates the binding of NH₄ ⁺ ions but loosely accommodates the biFrontiers in plant science571https://www.ebi.ac.uk/biostudies/studies/S-EPMC7256485biostudies-literatureFunctional Characterization of the <i>Arabidopsis</i> Ammonium Transporter AtAMT1;3 With the Emphasis on Structural Determinants of Substrate Binding and Permeation Properties.PMC7256485Liu SXZhou JYSentenac HHao DLVery AAHuang YNSu YHYang SYfalseFunctional Characterization of the <i>Arabidopsis</i> Ammonium Transporter AtAMT1;3 With the Emphasis on Structural Determinants of Substrate Binding and Permeation Properties.AtAMT1;3 is a major contributor to high-affinity ammonium uptake in <i>Arabidopsis</i> roots. Using a stable electrophysiological recording strategy, we demonstrate in <i>Xenopus laevis</i> oocytes that AtAMT1;3 functions as a typical high-affinity NH₄ ⁺ uniporter independent of protons and Ca²⁺. The findings that AtAMT1;3 transports methylammonium (MeA⁺, a chemical analog of NH₄ ⁺) with extremely low affinity (<i>K</i> _m in the range of 2.9-6.1 mM) led to investigate the mechanisms underlying substrate binding. Homologous modeling and substrate docking analyses predicted that the deduced substrate binding motif of AtAMT1;3 facilitates the binding of NH₄ ⁺ ions but loosely accommodates the bi2020-01-01T00:00:00Z20202026-05-04T12:44:21.435Z2020-06-14T07:07:04ZS-EPMC72564853252848910.3389/fpls.2020.00571