Assembly of the Mitochondrial Membrane System

Abstract

Abstract Yeast cells grown under conditions of glucose repression (5.4% glucose) exhibit a lower ATPase activity than cells grown on 0.8% glucose. The ATPase activity of the mitochondria increases during derepression, and this increase can be shown to be accompanied by an increase in the F1 (ATPase) content of the mitochondrial membranes. The increase of ATPase in the mitochondrial fraction during derepression is prevented by chloramphenicol. Under these conditions, however, there is an accumulation of soluble ATPase in the postribosomal supernatant. The soluble ATPase has been partially purified, and its properties indicate it to be identical to F1. Cycloheximide also prevents the increase of ATPase activity in the mitochondrial fraction during derepression. There is no accumulation of ATPase in the postribosomal fraction of cells incubated in a derepression medium containing cycloheximide. These results are interpreted to indicate that F1 is synthesized by the cytoplasmic-ribosomal protein-synthesizing system of the yeast cell.