The biogenesis of rat liver mitochondrial ATPase. Subunit composition of the normal ATPase complex and of the deficient complex formed when mitochondrial protein synthesis is blocked.

1. An ATPase complex containing 12 subunits was isoalted from rat liver mitochondria. 2. In vivo inhibition of mitochondrial protein synthesis by the chloramphenicol analogue thiamphenicol leads to the formation of an oligomycin-insensitive membrane-bound ATPase complex in mitochondria of regenerating rat liver. 3. This oligomycin-insensitive, membrane-bound ATPase was isolated by the same procedure as the ATPase complex from regenerating livers of untreated animals. 4. SDS-polyacrylamide gel electrophoresis of in vivo labelled ATPase complexes from control and from thiamphenicol-treated rats reveals that three subunits out of the 12 are not synthesized or assembled when the mitochondrial translation activity is blocked. 5. From the subunits synthesized and assembled when mitochondrial pror (Fo) of the ATPase complex (subunit 5). 6. The oligomycin sensitivity-conferring protein seems absent in the ATPase complex formed in the presence of thiamphenicol.