AGC kinase which plays a role in TOR complex 1 (TORC1) signaling pathway which mediates temporal control of cell growth in response to nutrients (PubMed:11062466). Required for phosphorylation of ribosomal protein S6 (RPS6A/RPS6B) at 'Ser-232' and 'Ser-233' (PubMed:25767889). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Phosphorylated by PKA in a TORC1-dependent manner. Phosphorylation at PKA consensus sites RRxS/T decreases upon rapamycin treatment. Present with 1470 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. S6 kinase subfamily.