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:8416931). V-ATPase is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:8416931, PubMed:2145285). Homodimer (PubMed:8626613). 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:2145285, PubMed:8416931, PubMed:25971514, PubMed:18055462, PubMed:27295975). Interacts with VMA5; the interaction is direct (PubMed:15751969). Interacts with VMA10; the interaction is direct (PubMed:15751969). Interacts with RAV1 and RAV2 components of the RAVE complex, which are essential for the stability and assembly of V-ATPase (PubMed:11283612). Present with 16134 molecules/cell in log phase SD medium. Belongs to the V-ATPase E subunit family.