Proton-conducting pore forming 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:1837023, PubMed:9030535). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:1837023, PubMed:9030535). 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) (PubMed:27776355, PubMed:29526695). The decameric c-ring forms the proton-conducting pore, and is composed of eight proteolipid subunits c, one subunit c' and one subunit c'' (PubMed:27776355, PubMed:29526695). Present with 538 molecules/cell in log phase SD medium. Belongs to the V-ATPase proteolipid subunit family.