Vacuolar H + -translocating inorganic pyrophosphatase [vacuolar H + -pyro-phosphatase (V-PPase); EC ] is a homodimeric proton translocase; it plays a pivotal role in electrogenic translocation of protons from the cyto-sol to the vacuolar lumen, at the expense of PPi hydrolysis, for the storage of ions, sugars, and other metabolites.