The function of Ensembl gene identifier ENSG00000105929 (ATP6V0A4, ATPase H+ transporting V0 subunit a4) is as follows. 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 normal vectorial acid transport into the urine by the kidney (PubMed:10973252, PubMed:12414817). {ECO:0000250|UniProtKB:Q29466, ECO:0000250|UniProtKB:Q93050, ECO:0000269|PubMed:10973252, ECO:0000269|PubMed:12414817}.