Predicted to contribute to proton-transporting ATPase activity, rotational mechanism. Involved in terminal branching, open tracheal system. Predicted to be part of plasma membrane proton-transporting V-type ATPase complex and vacuolar proton-transporting V-type ATPase complex. Predicted to be active in early endosome. Is expressed in adult head. Orthologous to human ATP6V0D1 (ATPase H+ transporting V0 subunit d1) and ATP6V0D2 (ATPase H+ transporting V0 subunit d2).