Plant vacuolar H+-transporting ATPases (V-ATPases) are ATP-driven proton pumps, located mainly in the vacuolar membrane, that generate proton motive force used to energize secondary active transports operating at the tonoplast. V-ATPases are the oldest and most complicated proton pumps found in plant cells. Enzyme subunits are divided into two major domains, the catalytic peripheral V1 domain responsible for ATP hydrolysis and the membrane-integral V domain responsible for H+ translocation.