Synthesis of Rat Liver Mitochondrial Proteins after the Administration of a Nonlethal Dose of Cycloheximide

Summary

Following in vivo treatment of rats with a nonlethal dose of cycloheximide (2 mg/kg body wt), analysis of the newly synthesized liver mitochondrial polypeptides by SDS-PAGE system showed: (i) sublethal levels of cycloheximide did transiently suppress synthesis and/or incorporation of large cytoplasmically synthesized proteins into mitochondria; (ii) synthesis and/or incorporation of this material was stimulated during the recovery phase. The differential labeling patterns of these mitochondrial proteins observed in vivo during cycloheximide treatment substantiate the cooperative nature of the cytoribosomal protein synthetic system to the formation of functional mitochondrion observed with mammalian cells in culture.

Fig. 3. Radioactivity profiles of soluble proteins extracted with acidic buffers from control and cycloheximidetreated (2 and 24 hr) mitochondria. For details see the legends to Figs. 1 and 2.

Fig. 4. Radioactivity profiles of soluble proteins extracted with alkaline buffers from control and cycloheximide-treated (2 and 24 hr) mitochondria. For details see the legends to Figs. 1 and 2.