A Vacuolar H+-ATPase inhibitor, IC50 = 0.6-1.5 nM in bovine chromaffin granules1. Highly selective for V-ATPase over F-ATPases and P-ATPase. Inhibits autophagy by preventing maturation of autophagic vacuoles via inhibition of fusion between autophagosomes and lysosomes2. Inhibits bone resorption in various models3. An extremely useful tool for exploring physiological processes regulated by V-ATPase4.