Cloning of an Arabidopsis histidine transporting protein related to nitrate and peptide transporters.

In plants, many of the proteins involved in transport of nitrogenous compounds have not been identified so far. The use of heterologous complementation in yeast mutants has enabled the isolation of a gene family encoding amino acid permease (AAP). A highly sensitive selection procedure was used to identify other proteins capable of transporting amino acids. In addition to members of the AAP gene family, an integral membrane protein (NTR1) that shows significant similarities to the low affinity nitrate transporter from Arabidpsis and to peptide transporters from yeast and rabbit was identified. NTR1 seems to be involved in the supply of reproductive organs with nitrogen as it is expressed at low levels in leaves and highly in developing pods.