In vitro protein synthesis in a mitochondrial fraction from HeLa cells: Sensitivity to antibiotics and ethidium bromide

Abstract

A mitochondrial fraction from HeLa cells which is contaminated by rough endoplasmic reticulum (E.R.) will, depending upon the conditions, support two types of in vitro protein synthesis. In the presence of soluble factors and an exogenous ATP generating system, the polysomes of the rough E.R. support protein synthesis which is sensitive to RNase and cycloheximide but insensitive to chloramphenicol, (CAP). In the absence of soluble factors, mitochondria are the exclusive site of protein synthesis: this can be supported either by an exogenous ATP generating system or by oxidative phosphorylation, is insensitive to RNase and cycloheximide and sensitive to CAP. The mitochondria) synthesis is sensitive to in vivo pre-treatment with ethidium bromide and decays with a half-life of 1–1.5 hr.