Phosphorylation of ribosomal proteins as a possible control system for protein synthesis. Binding of Met-tRNAf to 40 S ribosomal subunits.

The evidence that protein S6 of rat liver ribosomes is involved in P-site functions and that this protein is the main target of the small subunit for in vivo phosphorylation suggests that S6 phosphorylation may contribute to the regulation of protein synthesis. Therefore, we have studied the activity of small ribosomal subunits with unphosphorylated and phosphorylated protein S6 in Met-tRNAf binding. The results described in this paper show that at least under in vitro conditions S6 phosphorylation does obviously not influence the activity of small ribosomal subunits for eIF-2 dependent binding of initiator-tRNA.