NAR2 is a family of plant proteins with a C-terminal transmembrane region that is an essential accessory for high-affinity nitrate uptake [1]. This family works together with NRT2, a 12xTM family of proteins that is part of family MFS_1, Pfam:PF07690. NAR2 is also involved in the repression of lateral root initiation in response to high ratios of sucrose to nitrogen in the medium. Therefore the two component-system of NAR2 and NRT2 itself is likely to be involved in the signalling pathway that integrates nutritional cues for the regulation of lateral root architecture [2]. The functional unit of the high-affinity nitrate influx complex is likely to be a tetramer, in Arabidopsis, made up of two subunits each of NRT2.1 and NAR2.1 [3]. This entry corresponds to an immunoglobulin-like domain.

1: High-affinity nitrate transport in roots of Arabidopsis depends on expression of the NAR2-like gene AtNRT3.1. Okamoto M, Kumar A, Li W, Wang Y, Siddiqi MY, Crawford NM, Glass AD; Plant Physiol. 2006;140:1036-1046. PMID:16415212

2: Nitrate signaling and the two component high affinity uptake system in Arabidopsis. Orsel M, Chopin F, Leleu O, Smith SJ, Krapp A, Daniel-Vedele F, Miller AJ; Plant Signal Behav. 2007;2:260-262. PMID:19704673

3: Characterization of an intact two-component high-affinity nitrate transporter from Arabidopsis roots. Yong Z, Kotur Z, Glass AD; Plant J. 2010;63:739-748. PMID:20561257