Studies on the Role of Ribosomal Proteins L7 and L12 in the in Vitro Synthesis of β-Galactosidase

The DNA-directed in vitro synthesis of β-galactosidase has been examined in a system dependent on Escherichia coli ribosomes, a salt wash of the ribosomes, and a 200,000 x g supernatant fraction. The ribosomes can be replaced by 30 S and 50 S ribosomal subunits. Extraction of the 50 S particles with ethanol-NH4 yields inactive particles which can be reactivated equally well by the addition of either ribosomal protein L7 or L12.