Absence of a Free Ribosomal Protein Pool in Escherichia coli

Abstract

The presence of free ribosomal proteins was examined using anti-γ-globulin prepared against ribosomal proteins of Escherichia coli B. The anti-γ-globulin did not react with ribosome-free soluble proteins of E. coli cells by double diffusion test, immunoprecipitation test or gel filtration. Moreover, anti-γ-globulin did not react with any fractions of soluble proteins obtained by carboxymethyl cellulose-, DEAE-cellulose-or Sephadex G75-column chromatography. By mixing labeled ribosomes with unlabeled soluble proteins and vice versa and by comparing the specific activities of the ribosomes before and after mixing, ribosomal proteins were found to not exchange with any soluble protein in vitro. These results indicate that there is no pool of ribosomal protein in E. coli cells.