ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by cAMP. Present with 1590 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family. cAMP subfamily.