AtGAT1, a high affinity transporter for gamma-aminobutyric acid in Arabidopsis thaliana.
Functional characterization of Arabidopsis thaliana GAT1 in heterologous expression systems, i.e. Saccharomyces cerevisiae and Xenopus laevis oocytes, revealed that AtGAT1 (At1g08230) codes for an H(+)-driven, high affinity gamma-aminobutyric acid (GABA) transporter. In addition to GABA, other omega-aminofatty acids and butylamine are recognized. In contrast to the most closely related proteins of the proline transporter family, proline and glycine betaine are not transported by AtGAT1. AtGAT1 does not share sequence similarity with any of the non-plant GABA transporters described so far, and analyses of substrate selectivity and kinetic properties showed that AtGAT1-mediated transport is similar but distinct from that of mammalian, bacterial, and S. cerevisiae GABA transporters. Consistent with a role in GABA uptake into cells, transient expression of AtGAT1/green fluorescent protein fusion proteins in tobacco protoplasts revealed localization at the plasma membrane. In planta, AtGAT1 expression was highest in flowers and under conditions of elevated GABA concentrations such as wounding or senescence.
Meyer
Andreas
A
Institute of Plant Sciences, University of Bern, Altenbergrain 21, 3013 Bern, Switzerland.
Eskandari
Sepehr
S
Grallath
Silke
S
Rentsch
Doris
D
D000818:Animals; D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000502:physiology*; D001622:Betaine / Q000737:chemistry; D001667:Binding, Competitive; D001692:Biological Transport; D002082:Butylamines / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D016922:Cellular Senescence; D002734:Chlorophyll / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D004594:Electrophysiology; D004926:Escherichia coli / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D005998:Glycine / Q000737:chemistry; D049452:Green Fluorescent Proteins / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000737:chemistry / Q000502:physiology*; D008954:Models, Biological; D008956:Models, Chemical; D009865:Oocytes / Q000378:metabolism; D010802:Phylogeny; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D014176:Protein Biosynthesis; D011523:Protoplasts / Q000378:metabolism; D012313:RNA / Q000737:chemistry; D012333:RNA, Messenger / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D013379:Substrate Specificity; D014026:Nicotiana / Q000378:metabolism; D014945:Wound Healing; D014981:Xenopus / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D029681:Arabidopsis Proteins; D002082:Butylamines; C510128:GAT1 protein, Arabidopsis; D026901:Membrane Transport Proteins; D012333:RNA, Messenger; D002734:Chlorophyll; D049452:Green Fluorescent Proteins; D001622:Betaine; D005680:gamma-Aminobutyric Acid; D012313:RNA; D004247:DNA; D011392:Proline; D005998:Glycine