Ribosomal protein S6 (∽29kDa calculated and ∽32kDa observed molecular weights) is a component of the 40S ribosomal subunit and belongs to the S6E family of ribosomal proteins
The S6 ribosomal protein plays a role in regulating the translation of RNAs and thus controlling the growth and proliferation of cells
S6 ribosomal protein phosphorylation, especially at multiple C-terminal serine residues S235, S236, S240, and S244, activates S6
The activated S6 ribosomal protein in turn upregulates the ribosomal translation of RNA species coding for other ribosomal proteins, peptide elongation factors and other proteins involved in cell cycle entry and progression
These phosphorylations are mediated by various kinases (e.g., p70S6K and PKCD) activated through cellular responses to growth factors, cytokines, tumor promoting agents, and mitogens
The S6 ribosomal protein can be dephosphorylated in growth-arrested cells.