Fig. 3. Methylation of undermethylated ribosomal proteins by cell extracts enriched in YfcB. Ribosomes prepared from the prmB strain CL1447 (filled circles) or the wild-type parental strain AB2557 (open squares) were incubated with S-adenosyl-l-[methyl-³H]methionine and cell extract from cells overproducing YfcB. Control points (filled triangles) show the absence of methylation of undermethylated ribosomal proteins by a cell extract from the prmB strain CL1447. Each point corresponds to 12 pmol of ribosomes and 3 µg of cell extract protein (YfcB enriched) or 10 µg of cell extract (strain CL1447).