Activated enzyme phosphorylates target proteins and initiates downstream signaling pathways that shift metabolism from anabolic to catabolic pathways. Acts as a highly sensitive cellular energy sensor. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Heterotrimer of an alpha catalytic subunit, a beta and a gamma non-catalytic subunits. Expressed throughout development. Levels may increase during the first 5 hours of starvation-induced differentiation. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily.