Substrate Specificity and Expression Profile of Amino Acid Transporters (AAPs) in Arabidopsis

• Published in: The Journal of biological chemistry Vol. 270; no. 27; pp. 16315 - 16320
• Main Authors: Fischer, Wolf-N., Kwart, Marion, Hummel, Sabine, Frommer, Wolf B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07-07-1995; American Society for Biochemistry and Molecular Biology
• Subjects: AAP3 GENE; AAP4 GENE; AAP5 GENE; ACIDE AMINE; ACTIVE TRANSPORT; Amino Acid Sequence; AMINO ACID SEQUENCES; Amino Acid Transport Systems; AMINO ACIDS; Amino Acids - metabolism; AMINOACIDOS; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; ARABIDOPSIS THALIANA; ARN MENSAJERO; ARN MESSAGER; Biological Transport, Active - genetics; Blotting, Southern; CELL MEMBRANES; CHEMICAL COMPOSITION; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; EXPRESION GENICA; EXPRESSION DES GENES; FEUILLE; FLEUR; FLORES; FLOWERS; GENBANK/X77499; GENBANK/X77500; GENBANK/X77501; GENE; GENE EXPRESSION; GENE TRANSFER; GENES; Genetic Complementation Test; Genome, Plant; HOJAS; Hydrogen-Ion Concentration; LEAVES; MEMBRANAS CELULARES; MEMBRANE CELLULAIRE; Membrane Transport Proteins - genetics; Membrane Transport Proteins - metabolism; MESSENGER RNA; MOLECULAR SEQUENCE DATA; NUCLEOTIDE SEQUENCE; PLANT PROTEINS; Plant Proteins - metabolism; PLASMA MEMBRANES; Protein Structure, Secondary; PROTEINAS; PROTEINE; PROTEINS; RACINE; RAICES; Recombinant Proteins - metabolism; ROOTS; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; SECUENCIA NUCLEOTIDICA; Sequence Homology, Amino Acid; SEQUENCE NUCLEOTIDIQUE; STEMS; STRUCTURAL GENES; Substrate Specificity; TALLO; TIGE; Tissue Distribution; TRANSFERENCIA DE GENES; TRANSFERT DE GENE
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.270.27.16315

Three amino acid transporter genes (AAP3-5) were isolated from Arabidopsis by complementation of a yeast mutant defective in histidine uptake. Transport is driven against a concentration gradient and sensitive to protonophores. Analysis of the substrate specificity demonstrates that the carriers have a broad substrate specificity covering the major transport forms of reduced nitrogen, i.e. glutamine and glutamate. The transporters have similar affinities for glutamate, glutamine, and alanine but differ with respect to valine, phenylalanine, histidine, arginine, and lysine. AAP3 and AAP5 efficiently transport arginine and lysine and are involved in basic amino acid transport. The predicted polypeptides of 53 kDa are highly hydrophobic with 12 putative membrane-spanning regions and show significant homologies to Arabidopsis amino acid transporters AAP1 and AAP2. Each of the genes has a different organ-specific expression in the plant. AAP3 is exclusively expressed in roots and AAP4 mainly in source leaves, stems, and flowers, whereas AAP5 is found in all tissues. The specific distribution in the plant and the different substrate specificities of AAP transporters may indicate that tissues differ both qualitatively and quantitatively regarding import or export of amino acids.