Assembly of the Mitochondrial Membrane System

Abstract

Abstract The rutamycin-sensitive ATPase complex of yeast mitocondria consists of the ATPase, F1, of an easily extractable protein (OSCP) which is concerned with the binding of F1 to the membrane, and of another membrane factor which contains at least four distinct subunit proteins. When glucose-repressed yeast are incubated in a low glucose medium containing cycloheximide and radioactive leucine, label is incorporated into a fraction which forms a precipitable complex with antiserum to the rutamycin-sensitive ATPase. Analysis of the antibody precipitate by gel electrophoresis has revealed that at least four distinct proteins are labeled. The labeled products comigrate with known subunits of the rutamycin-sensitive ATPase and comprise those protein components of the ATPase which are most firmly associated with the membrane. These results indicate that with the exception of F1 and OSCP, which are synthesized in the cytoplasm, the remaining subunits of the ATPase are made by the mitochondrion.