Potential-dependent anion transport across tonoplast vesicles from oat roots

Conference · Tue Apr 01 04:00:00 EST 1986 · Plant Physiol., Suppl.; (United States)

OSTI ID:5017983

Kaestner, K H; Sze, H

Potential-dependent anion movement was monitored as dissipation of membrane potentials using the fluorescence probe Oxonol V. The potentials (positive inside) were generated with the H/sup +/-pumping pyrophosphatase (PPase) associated with tonoplast vesicles. Unlike the H/sup +/-ATPase, the PPase is stimulated by K/sup +/ and insensitive to anions. The order of permeability for the anions tested was: SCN/sup -/ > Cl/sup -/ = NO/sub 3//sup -/ > Br/sup -/ >> SO/sub 4//sup =/ = H/sub 2/PO/sub 4//sup -/ > acetate = malate > iminodiacetate. Kinetic studies showed that the Cl/sup -/ and NO/sub 3//sup -/ transport activities are saturable (Km = 2 and 5 mM), indicating the existence of proteinaceous anion channels. In contrast to the H/sup +//Cl/sup -/ symporter identified in the same vesicles, the potential-dependent Cl/sup -/ transport was insensitive to 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid. These results suggest the existence of at least two different mechanisms for Cl/sup -/ transport in these vesicles. The potentials generated by the H/sup +/-ATPase and the H/sup +/-PPase were non-additive, giving further support to the notion that both enzymes are on the same population of vesicles.

• Research Organization: Univ. of Maryland, College Park
• OSTI ID: 5017983
• Conference Information: Journal Name: Plant Physiol., Suppl.; (United States) Journal Volume: 80:4
• Country of Publication: United States
• Language: English

Related Subjects

551000* -- Physiological Systems
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ANIONS
ATP-ASE
CELL CONSTITUENTS
CELL MEMBRANES
CEREALS
CHARGED PARTICLES
CHLORINE
ELEMENTS
ENZYME ACTIVITY
ENZYMES
GRASS
HALOGENS
HYDROLASES
IONS
MEMBRANE TRANSPORT
MEMBRANES
NITRATES
NITROGEN COMPOUNDS
NONMETALS
OATS
OXYGEN COMPOUNDS
PHOSPHOHYDROLASES
PLANT CELLS
PLANTS
ROOTS