Photolabeling of tonoplast from sugar beet cell suspensions by ( sup 3 H)5-(N-methyl-N-isobutyl)-amiloride, an inhibitor of the vacuolar Na sup + /H sup + antiport. [Beta vulgaris L]

Journal Article · Sun Jul 01 00:00:00 EDT 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.93.3.924· OSTI ID:5914777

Barkla, B J; Charuk, J H.M.; Blumwald, E ^[1]; Cragoe, Jr, E J

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1. Univ. of Toronto, Ontario (Canada)

The effects of 5-(N-methyl-N-isobutyl)-amiloride (MIA), an amiloride analog, was tested on the Na{sup +}/H{sup +} antiport activity of intact vacuoles and tonoplast vesicles isolated from sugar beet (Beta vulgaris L.) cell suspension cultures. MIA inhibited Na{sup +}/H{sup +} exchange in a competitive manner with a K{sub i} of 2.5 and 5.9 micromolar for {Delta}pH-dependent {sup 22}Na{sup +} influx in tonoplast vesicles and Na{sup +}-dependent H{sup +} efflux in intact vacuoles, respectively. Scatchard analysis of the binding of ({sup 3}H)MIA to tonoplast membranes revealed a high affinity binding component with a K{sub d} of 1.3 micromolar. The close relationship between the dissociation constant value obtained and the constants of inhibition for MIA obtained by fluorescence quenching and isotope exchange suggests that the high affinity component represents a class of sites associated with the tonoplast Na{sup +}/H{sup +} antiport. Photolabeling of the tonoplast with ({sup 3}H)MIA revealed two sets of polypeptides with a different affinity to amiloride and its analog.

• OSTI ID: 5914777
• Journal Information: Plant Physiology; (USA), Vol. 93:3; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
BEETS
PHYSIOLOGY
PLANT CELLS
MEMBRANE TRANSPORT
HYDROGEN COMPOUNDS
SODIUM 22
SODIUM COMPOUNDS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
FOOD
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAGNOLIOPHYTA
MAGNOLIOPSIDA
NUCLEI
ODD-ODD NUCLEI
PLANTS
RADIOISOTOPES
SODIUM ISOTOPES
VEGETABLES
YEARS LIVING RADIOISOTOPES
551001* - Physiological Systems- Tracer Techniques