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Photolabeling of Tonoplast From Sugar Beet Cell Suspensions by [h]5-(N-methyl-N-isobutyl)-amiloride, an Inhibitor of the Vacuolar na/h Antiport

Photolabeling of Tonoplast From Sugar Beet Cell Suspensions by [h]5-(N-methyl-N-isobutyl)-amiloride, an Inhibitor of the Vacuolar na/h Antiport

B J Barkla, J H Charuk, E J Cragoe, E Blumwald

Plant Physiol. 1990 Jul;93(3):924-30.

PMID: 16667602

Abstract:

The effects of 5-(N-methyl-N-isobutyl)-amiloride (MIA), an amiloride analog, was tested on the Na(+)/H(+) antiport activity of intact vacuoles and tonoplast vesicles isolated from sugar beet (Beta vulgaris L.) cell suspension cultures. MIA inhibited Na(+)/H(+) exchange in a competitive manner with a K(i) of 2.5 and 5.9 micromolar for DeltapH-dependent (22)Na(+) influx in tonoplast vesicles and Na(+)-dependent H(+) efflux in intact vacuoles, respectively. Scatchard analysis of the binding of [(3)H]MIA to tonoplast membranes revealed a high affinity binding component with a K(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(+)/H(+) antiport. Photolabeling of the tonoplast with [(3)H]MIA revealed two sets of polypeptides with a different affinity to amiloride and its analog.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP96861653	5-(N-Methyl-N-isobutyl)amiloride		96861-65-3	Price

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