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). V-ATPase is responsible for acidifying a variety of intracellular organelles in eukaryotic cells, thus providing most of the energy required for transport processes in the vacuolar system. ATP6V0D1 is a subunit of the integral membrane V0 complex of vacuolar ATPase.