Subunit of the V0 complex of vacuolar(H+)-ATPase (V-ATPase), a multisubunit enzyme composed of a peripheral complex (V1) that hydrolyzes ATP and a membrane integral complex (V0) that translocates protons (PubMed:7514599, PubMed:11278748). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:11278748, PubMed:7514599). Is present only in Golgi- and endosome-residing V-ATPase complexes; enzymes containing this subunit have a 4-fold lower ratio of proton transport to ATP hydrolysis than complexes containing the vacuolar isoform and do not dissociate V1 and V0 in response to glucose depletion (PubMed:11278748, PubMed:7514599). 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'', d, e, f and VOA1). Glycosylated. Present with 1084 molecules/cell in log phase SD medium. Belongs to the V-ATPase 116 kDa subunit family.