Seed and vascular expression of a high-affinity transporter for cationic amino acids in Arabidopsis.
In most plants amino acids represent the major transport form for organic nitrogen. A sensitive selection system in yeast mutants has allowed identification of a previously unidentified amino acid transporter in Arabidopsis. AAT1 encodes a hydrophobic membrane protein with 14 membrane-spanning regions and shares homologies with the ecotropic murine leukemia virus receptor, a bifunctional protein serving also as a cationic amino acid transporter in mammals. When expressed in yeast, AAT1 mediates high-affinity transport of basic amino acids, but to a lower extent also recognizes acidic and neutral amino acids. AAT1-mediated histidine transport is sensitive to protonophores and occurs against a concentration gradient, indicating that AAT1 may function as a proton symporter. AAT1 is specifically expressed in major veins of leaves and roots and in various floral tissues--i.e., and developing seeds.
Frommer
W B
WB
Institut für Genbiologische Forschung, Berlin, Germany.
Hummel
S
S
Unseld
M
M
Ninnemann
O
O
D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems; D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D018076:DNA, Complementary; D015723:Gene Library; D017343:Genes, Plant; D005816:Genetic Complementation Test; D006801:Humans; D007700:Kinetics; D009052:Leukemia Virus, Murine / Q000378:metabolism; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000737:chemistry / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D011487:Protein Conformation; D012639:Seeds; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana
C097331:AAT1 protein, Arabidopsis; D026905:Amino Acid Transport Systems; D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids; D029681:Arabidopsis Proteins; D002352:Carrier Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins