title: Identification and characterization of GABA, proline and quaternary ammonium compound transporters from Arabidopsis thaliana.
abstract: Arabidopsis thaliana grows efficiently on GABA as the sole nitrogen source, thereby providing evidence for the existence of GABA transporters in plants. Heterologous complementation of a GABA uptake-deficient yeast mutant identified two previously known plant amino acid transporters, AAP3 and ProT2, as GABA transporters with Michaelis constants of 12.9 +/- 1.7 and 1.7 +/- 0.3 mM at pH 4, respectively. The simultaneous transport of [1-14C]GABA and [2,3-3H]proline by ProT2 as a function of pH, provided evidence that the zwitterionic state of GABA is an important parameter in substrate recognition. ProT2-mediated [1-14C]GABA transport was inhibited by proline and quaternary ammonium compounds.
authors.affiliation: Plant Physiology, ZMBP-Zentrum für Molekularbiologie der Pflanzen, University of Tübingen, Germany.
authors.forename: K E
authors.initials: KE
authors.lastname: Breitkreuz
authors.forename: B J
authors.initials: BJ
authors.lastname: Shelp
authors.forename: W N
authors.initials: WN
authors.lastname: Fischer
authors.forename: R
authors.initials: R
authors.lastname: Schwacke
authors.forename: D
authors.initials: D
authors.lastname: Rentsch
mesh_terms: D026905:Amino Acid Transport Systems; D026921:Amino Acid Transport Systems, Neutral; D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism*; D005816:Genetic Complementation Test; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D016296:Mutagenesis; D011392:Proline / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D026905:Amino Acid Transport Systems; D026921:Amino Acid Transport Systems, Neutral; D026901:Membrane Transport Proteins; D005680:gamma-Aminobutyric Acid; C033082:proline transporter; D011392:Proline