Ribosomal protein S6 kinase beta-1 (RPS6KB1)

Regulates protein synthesis through phosphorylation of EIF4B, RPS6 and EEF2K, and contributes to cell survival by repressing the pro-apoptotic function of BAD. Under conditions of nutrient depletion, the inactive form associates with the EIF3 translation initiation complex.

Upon mitogenic stimulation, phosphorylation by the mammalian target of rapamycin complex 1 (mTORC1) leads to dissociation in the EIF3 complex and activation. The active form then phosphorylates and activates several substrates from the pre-initiation complex, including the EIF2B complex and the cap-binding complex component EIF4B.