CLONING OF AN ARABIDOPSIS HISTIDINE TRANSPORTING PROTEIN RELATED TO NITRATE AND PEPTIDE TRANSPORTERS

In plants, many of the proteins involved in transport of nitrogenous c ompounds have not been identified so far. The use of heterologous comp lementation in yeast mutants has enabled the isolation of a gene famil y encoding amino acid permease (AAP). A highly sensitive selection pro cedure was used to identify other proteins capable of transporting ami no acids. In addition to members of the AAP gene family, an integral m embrane protein (NTR1) that shows significant similarities to the low affinity nitrate transporter from Arabidopsis and to peptide transport ers 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.