Chloride-ion stimulation of the tonoplast H+-translocating ATPase from Hevea brasiliensis (rubber tree) latex. A dual mechanism.
The effect of Cl- and other anions on the tonoplast H+-translocating ATPase (H+-ATPase) from Hevea brasiliensis (rubber tree) latex was investigated. Cl- and other anions stimulated the ATPase activity of tightly sealed vesicles prepared from Hevea tonoplast, with the following decreasing order of effectiveness: Cl- greater than Br- greater than SO4(2-) greater than NO3-. As indicated by the changes of the protonmotive potential difference, anion stimulation of tonoplast H+-ATPase was caused in part by the ability of these anions to dissipate the electrical potential. This interpretation assumes not a channelling of these anions against a membrane potential, negative-inside, but a modification of the permeability of these ions through the tonoplast membrane. In addition, Cl- and the other anions stimulated the ATPase activity solubilized from the tonoplast membrane. Consequently, the tonoplast H+-pumping ATPase can be considered as an anion-stimulated enzyme. These results are discussed in relation to various models described in the literature for the microsomal H+-ATPase systems claimed as tonoplast entities.
Marin
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D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000838:Anions / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D006096:Gramicidin / Q000502:physiology; D007425:Intracellular Membranes / Q000187:drug effects / Q000201:enzymology; D008564:Membrane Potentials / Q000187:drug effects; D010944:Plants / Q000187:drug effects / Q000201:enzymology*; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014197:Trees
D000838:Anions; D002712:Chlorides; D006096:Gramicidin; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D006180:Proton-Translocating ATPases; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid