Vacuolar ATPase (V ATPase) is a heteromultimeric enzyme composed of a peripheral catalytic V1 complex (components A to H) attached to an integral membrane V0 proton pore complex (components: a, c, c', c'' and d). It is responsible for acidifying a variety of intracellular organelles in eukaryotic cells. ATP6V0D2 is a component of the integral membrane V0 complex of vacuolar ATPase and may have a role in coupling of proton transport and ATP hydrolysis. ATP6V0D2 may be involved in regulation of osteoclast fusion and bone formation.