Assembly of the Mitochondrial Membrane System: VII. SYNTHESIS AND INTEGRATION OF F1 SUBUNITS INTO THE RUTAMYCIN-SENSITIVE ADENOSINE TRIPHOSPHATASE

Abstract

Abstract The rutamycin-insensitive ATPase (F1) of yeast mitochondria was found in previous studies to be synthesized on the cytoplasmic ribosomes and to accumulate in the postribosomal supernatant (Tzagoloff, A. (1969) J. Biol. Chem. 244, 5027). The enzyme has been purified from the postribosomal fraction of yeast grown in the presence of chloramphenicol and compared with F1 isolated from normal yeast mitochondria. The subunit protein compositions of the two preparations are identical, indicating that all of the component proteins of F1 are products of the cytoribosomal system of protein synthesis. Following removal of chloramphenicol and further incubation of the cells in growth medium (derepression), an increase of the ATPase activity of mitochondria and a loss of F1 activity in the postribosomal supernatant are observed. Evidence is presented indicating that during derepression the postribosomal F1 is incorporated into the larger rutamycin-sensitive ATPase complex of mitochondria.