Vacuolar-type Proton Translocating ATPase

Vacuolar-type proton translocating ATPase is a heter-eomeric protein complex, which appears to translocate two protons across the vesicle membrane for each ATP molecule that is hydrolyzed, generating chemical (ApH) and electrical (A ) gradients. Although the ATPases present on different classes of intracellular vesicle have... 

Synaptic vesicles isolated from brain exhibit four distinct vesicular neurotransmitter transport activities one for monoamines, a second for acetylcholine, a third for the inhibitory neurotransmitters GABA and glycine, and a fourth for glutamate [1], Unlike Na+-dependent plasma membrane transporters, the vesicular activities couple to a proton electrochemical gradient (A. lh+) across the vesicle membrane generated by the vacuolar H+-ATPase ( vacuolar type proton translocating ATPase). Although all of the vesicular transport systems rely on ApH+, the relative dependence on the chemical and electrical components varies (Fig. 1). The... 

Three types of ATP-driven cation pumps can be distinguished on the basis of their structure and their sensitivity to inhibitors. They are the E E2-ATPases, the FiFo-proton-translocating ATP synthase, and the vacuolar ATPases which are designated as P-, F-, and V-type ATPases, respectively [37]. Several of the distinguishing characteristics of these enzymes are summarized in Table 1. The F- and V-ATPases can be differentiated by the sensitivity of the former to azide and the latter to nitrate and A-ethylmaleimide (NEM)[38]. In addition, the V-ATPases are exquisitely sensitive to the antibiotic bafilomycin A [39,40]. 

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