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 (By similarity). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments and in some cell types, is targeted to the plasma membrane, where it is responsible for acidifying the extracellular environment (By similarity). Involved in the assembly of the V-ATPase complex (PubMed:17179093). The V-ATPase is required for the function of the excretory canal (PubMed:16785323, PubMed:17179093). Independently of the V1 complex, the V0 complex of the V-ATPase is required for multivesicular body membrane fusion with the apical membrane of the epidermal cells during exosome release and thus regulates the release of cuticle components such as Hedgehog-related peptide wrt-2 but not collagen (PubMed:16785323). Also, in the epidermis, regulates the trafficking of che-14 and rdy-2 (PubMed:17179093). Regulates the secretion of granular material found in the amphid channel and in controlling osmoregulation in the amphid pocket (PubMed:17179093). V-ATPase is a heteromultimeric enzyme made up of two complexes: the ATP-hydrolytic V1 complex and the proton translocation V0 complex (By similarity). The V1 complex consists of three catalytic AB heterodimers that form a heterohexamer, three peripheral stalks each consisting of EG heterodimers, one central rotor including subunits D and F, and the regulatory subunits C and H (By similarity). The proton translocation complex V0 consists of the proton transport subunit a, a ring of proteolipid subunits c9c'', rotary subunit d, subunits e and f, and the accessory subunits vah-19/Ac45 and vah-20/PRR (By similarity). Interacts with V-type proton ATPase subunit C vha-11 (PubMed:11441002). In embryos, localizes to dot-like compartments or in cup-shaped structures (PubMed:11441002). Localizes to multivesicular body membranes in the epidermis (PubMed:16785323). Colocalizes with vha-8 to stacked sheets of the apical cell membrane of syncytial hypodermal cells (PubMed:16785323). In the epidermis, localizes to dispersed spots during intermolts which becomes aligned and colocalizes with actin bundles during the molts (PubMed:17179093). Expressed in the H-shaped excretory cell (at protein level) (PubMed:11441002, PubMed:16785323, PubMed:17179093). Expressed in hypodermal cells around the vulva (PubMed:11441002). Expressed in the main epidermal syncytium (PubMed:16785323, PubMed:17179093). Expressed in the sheath cells associated with head and tail sensory organs; specifically, expressed in the apical sheath cells of the amphids and CEP neuron and in the sheath cells of the OLQ sensory organ (PubMed:17179093). Expressed in embryos (at protein level) (PubMed:11441002). Expressed in the H-shaped excretory cell and pharynx in L2 larvae and adults (PubMed:11441002). RNAi-mediated knockdown causes larval lethality at the L2 stage (PubMed:11441002, PubMed:16785323). RNAi-mediated knockdown causes defects in alae formation in L1 larvae and in the few surviving adults (PubMed:16785323). Shorter body length (PubMed:16785323). Belongs to the V-ATPase 116 kDa subunit family.