ATP synthase alpha/beta subunits
The alpha and beta (or A and B) subunits are found in the F1, V1, and A1 complexes of F-, V- and A-ATPases, respectively, as well as flagellar (T3SS) ATPase and the termination factor Rho. The subunits make up a ring that contains the ATP-hydrolyzing (or producing) catalytic core.
Source: Wikipedia — ATP synthase alpha/beta subunits (CC BY-SA 4.0)