Involved in nitrate transport. Expressed in the base of the lateral root primordia, root-shoot junction zone, leaves, ends of the husk and vascular tissue of the anthers. Circadian-regulation with a peak in the middle of the morning. Induced by nitrate and sucrose in roots. Down-regulated by glutamine, gluatamate, asparagine and aspartate in roots. Belongs to the major facilitator superfamily. Nitrate/nitrite porter (TC 2.A.1.8) family.