Assembly of the yeast mitochondrial H+ATPase: regulation by the overproduction and availability of the nuclear encoded (F1) subunits

The assembly of the mitochondrial ATPase was studied in vitro by incubating isolated yeast mitochondria with radiolabeled mitochondrial precursors and in vivo by pulse-labeling of intact yeast cells and spheroplasts. Newly assembled F1 ATPase (radiolabeled) was assayed by immunoprecipitation using subunit-specific antisera directed to the α subunit of the complex. Using two different experimental approaches, the authors have provided evidence suggesting that isolated mitochondria possess pools of unassembled F1α subunits and possibly F1β subunits. In addition, the kinetics of import suggest that the F1β subunit was imported and assembled at a slower rate than either the F1α and F1γ subunits. Thus, the appearance of the new ATPase could be limited by the availability of the β subunits