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Calmodulin dependent formation of membrane potential in barley root plasma membrane vesicles: A biochemical model of aluminum toxicity in plants
Author(s) -
Siegel Neal,
Hang Alfred
Publication year - 1983
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1983.tb00772.x
Subject(s) - calmodulin , vesicle , membrane , biophysics , chemistry , atpase , calcium , biochemistry , enzyme , membrane potential , fluorescence , transmembrane protein , biology , receptor , physics , organic chemistry , quantum mechanics
Micromolar concentrations of aluminum ions interfere with calmodulin‐stimulated, membrane bound ATPase activity which plays a role in the maintenance of the transmembrane potential of plasma membrane enriched vesicles isolated from barley roots. Calmodulin appears to be the major target for aluminum interaction resulting in pronounced changes in the exposure of a large, hydrophobic surface on this protein as determined with a fluorescent, hydrophobic surface probe. At a molar ratio of 3:1 [aluminum]/[calmodulin], the calmodulin stimulated enzymatic activity, probably associated with a Ca 2+ + Mg 2+ ATPase, is about 95% inhibited. Aluminum induced changes in calmodulin structure are reflected in reduced formation of the membrane potential when assayed with a fluorescent potential probe, oxonol VI. We hypothesize that the aluminum caimodulin complex represents a primary lesion in toxic responses of plants to this metal.