Catalytic subunit of the V1 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:25220074). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:25220074). Mediates oxidative stress response, filamentous growth, and plays an important role in virulence (PubMed:25220074). ATP + 4 H(+)(in) + H2O = ADP + 5 H(+)(out) + phosphate 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). Localizes in cytoplasm under glucose deprivation conditions and to the vacuolar membrane in presence of glucose. Is a probable target for sumoylation. Leads to a defect in vacuolar acidification and higher sensitivity to oxidants such as H(2)O(2) or menadione. Reduces strongly virulence in mice. Belongs to the ATPase alpha/beta chains family.