SpoIIIJ and YqjG restore reduction of ATPase activity due to YidC depletion. The activity of the F1Fo ATPase was determined by measuring the release of inorganic phosphate upon addition of ATP to IMVs. Lane 1, wild-type Ara; lane 2, wild-type Glu; lane 3, YidC-depleted IMVs; lane 4, YidC-depleted IMVs plus SpoIIIJ; lane 5, YidC-depleted IMVs plus YqjG. The levels of Foc were determined by immunoblotting. α-F0c, anti-Foc.