Catalytic site occupancy of the yeast vacuolar V-ATPase during ATP hydrolysis in the presence of an ATP-regenerating system was probed using sensitivity of the enzyme to inhibition by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl). The results show that, regardless of the presence or absence of the proton-motive force across the vacuolar membrane, saturation of V-ATPase activity at increasing MgATP concentrations is accompanied by only partial protection of the enzyme from inhibition by NBD-Cl. Both in the presence and absence of an uncoupler, complete protection of V-ATPase from inhibition by NBD-Cl requires MgATP concentrations that are significantly higher than those expected from the K(m) values for MgATP. The results are inconsistent with a tri-site model and support a bi-site model for a mechanism of ATP hydrolysis by V-ATPase.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|