Decrease of pH gradients in tonoplast vesicles by NO/sub 3//sup -/ and Cl/sup -/: evidence for H/sup +/-coupled anion transport
Chloride or nitrate decreased a pH gradient (measured as (/sup 14/C)methylamine accumulation) in tonoplast-enriched vesicles. The ..delta..pH decrease was dependent on the anion concentration. These effects are independent of the anion-sensitive H/sup +/-ATPase of the tonoplast, since the pH gradient (acid inside) was imposed artificially using a pH jump or a K/sup +/ gradient and nigericin. 4,4'-Diisothiocyano-2,2'-stilbene disulfonic acid partially prevented the decrease in pH gradient induced by Cl/sup -/. Two possible models to account for this anion-dependent decrease of ..delta..pH are: (a) H/sup +/ loss is accompanied by Cl/sup -/ or NO/sub 3//sup -/ efflux from the vesicles via H/sup +//anion symport systems on the tonoplast and (b) H/sup +/ loss is accompanied by Cl/sup -/ or NO/sub 3//sup -/ uptake into the vesicles via H/sup +//anion antiport systems. Depending on the requirements and conditions of the cell, these two systems would serve to either mobilize Cl/sup -/ and NO/sub 3//sup -/ stored in the vacuole for use in the cytoplasm or to drive anions into the vacuole. Chloride or nitrate also decreased a pH gradient in fractions containing plasma membrane and Golgi, implying that these membranes may have similar H/sup +/-coupled anion transport systems.
- Research Organization:
- Univ. of Maryland, College Park
- DOE Contract Number:
- AS05-82ER13015
- OSTI ID:
- 6401450
- Journal Information:
- Plant Physiol.; (United States), Journal Name: Plant Physiol.; (United States) Vol. 83:3; ISSN PLPHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
560300* -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIONS
CARBON 14 COMPOUNDS
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
CHLORIDES
CHLORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
IONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
MEMBRANE TRANSPORT
MEMBRANES
NITRATES
NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PH VALUE
TRACER TECHNIQUES