title: Citrate uptake into tonoplast vesicles from acid lime (Citrus aurantifolia) juice cells.
abstract: Citrate transport into the vacuoles of acid lime juice cells was investigated using isolated tonoplast vesicles. ATP stimulated citrate uptake in the presence or in the absence of a Delta mu H+. Energization of the vesicles only by an artificial K+ gradient (establishing an inside-positive Delta psi) also resulted in citrate uptake as was the case of a Delta pH dominated Delta mu H+. Addition of inhibitors to endomembrane ATPases showed no direct correlation between the inhibition to the tonoplast bound H+/ATPase and citrate uptake. The data indicated that, although some citrate uptake can be accounted for by Delta psi and by a direct primary active transport mechanism involving ATP, under in vivo conditions of vacuolar pH of 2.0, citrate uptake is driven by Delta pH.
authors.affiliation: The University of Florida, IFAS, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850, USA.
authors.forename: A
authors.initials: A
authors.lastname: Brune
authors.forename: P
authors.initials: P
authors.lastname: Gonzalez
authors.forename: R
authors.initials: R
authors.lastname: Goren
authors.forename: U
authors.initials: U
authors.lastname: Zehavi
authors.forename: E
authors.initials: E
authors.lastname: Echeverria
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D001693:Biological Transport, Active; D002951:Citrates / Q000378:metabolism*; D002957:Citrus / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008274:Magnesium / Q000494:pharmacology; D018087:Plastids / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D014617:Vacuoles / Q000378:metabolism*
chemical_list: D002951:Citrates; D000255:Adenosine Triphosphate; D008274:Magnesium; D011188:Potassium