Ribosomes, the organelles that catalyze protein synthesis, consist of a small 40S subunit and a large 60S subunit. Ribosomal protein S6 is the major substrate of protein kinases in eukaryote ribosomes. The phosphorylation is stimulated by growth factors, tumor promoting agents, and mitogens.Dephosphorylation occurs at growth arrest. The protein may contribute to the control of cell growth and proliferation through the selective translation of particular classes of mRNA.
