Abstract
When rabbit reticulocytes were incubated in vitro with [(3)H]acetate, their ribosomal proteins were rapidly acetylated within 10 min. Polyacrylamide-urea gel electrophoresis showed that several major ribosomal protein fractions were highly acetylated. By the double-isotope labeling technique, the incorporation of [(3)H]acetate and [(14)C]aminoacid mixture into ribosomal proteins and nascent chains was found to be closely associated. Sodium fluoride abolished the acetylation of ribosomal proteins, whereas cycloheximide reduced the acetylation of ribosomal proteins to a much lower level. These findings suggest that acetylation of ribosomal proteins may be involved in the formation of the initiation complex during protein biosynthesis.