Ribosomal protein in E. coli: rate of synthesis and pool size at different growth rates

Summary Relative rates of ribosomal protein synthesis _r was determined by pulsechase labeling of cell protein followed by isolation of ribosomes by electrophoresis of complete lysates on agarose gels. The agarose gel fractionation of lysates is described in detail. Cells growing in acetate, glucose and enriched glucose media had _r values of 0.09, 0.16, and 0.24, respectively. Estimates of the free pool of ribosomal protein were obtained from the kinetics of pulse-chase labeling of ribosomal particles (including precursor particles) and gave maximal values of 1.1, 2.1, and 3.1% of total ribosomal protein at the three different growth rates. The kinetics indicate that the free concentrations in the cell are not the same for all ribosomal proteins.