Effect of surface and membrane potentials on IAA (indoleactic acid) uptake and binding by zucchini membrane vesicles

Conference · Fri Aug 01 04:00:00 EDT 1986

OSTI ID:7035692

Clark, K A; Goldsmith, M H.M.

The polar transport of the endogenous hormone controlling extension growth of plant cells, indoleacetic acid (IAA), is thought to depend on transmembrane pH and electrical gradients resulting in part from the action of proton ATPases in the plasma membrane. Elements of this transport process are permeation of the membrane by the undissociated lipophilic indoleacetic acid (IAAH) from the acidic apoplast, followed by dissociation of the weak acid and accumulation of the IAA anion (IAA/sup -/) in the alkaline cytoplasm; a saturable symport of IAA/sup -/ with one or more protons; a carrier-mediated efflux of IAA/sup -/ down a considerable electrochemical gradient. The efflux is greater from the basal than the apical end of cells and is thought to be responsible for the overall polarity of the process. This step is also the site of action of napthylphthalamic acid (NPA) and herbicides that inhibit polar transport but stimulate net accumulation of auxin by tissues and cells. We are using membrane vesicles as a simplified system for studying the mechanisms involved in the transport and accumulation of auxin. In particular, we are interested in determining the involvement of the transmembrane pH (pH/sub o/ < pH/sub i/) and voltage gradients (K/sup +/ diffusion potential, (K/sup +/)/sub in/ > (K/sup +/)/sub out/) in IAA uptake. 19 refs., 6 figs.

• Research Organization: Yale Univ., New Haven, CT (USA). Dept. of Biology
• DOE Contract Number: FG02-85ER13337
• OSTI ID: 7035692
• Report Number(s): CONF-8608155-1; ON: DE87003222
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
551001 -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
CELL CONSTITUENTS
ELECTROPHYSIOLOGY
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIPOSOMES
MEMBRANE PROTEINS
MEMBRANE TRANSPORT
ORGANIC COMPOUNDS
ORGANOIDS
PHYSIOLOGY
PLANT GROWTH REGULATORS
PROTEINS
RECEPTORS
TRACER TECHNIQUES
TRITIUM COMPOUNDS