Involved in a signaling module for sexual development and cell growth under stressed conditions. Required for G1 arrest under nitrogen starvation and for growth at high temperature and osmolarity. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Phosphorylated by ksg1 and target of rapamycin complex 2 (TORC2), affecting the kinase activity of gad8 in a nutrient-dependent manner. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family.