Calcium/calmodulin-dependent protein kinase belonging to a proposed calcium-triggered signaling cascade. In vitro phosphorylates transcription factor CREB1 (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by Ca(2+)/calmodulin. Binding of calmodulin is thought to result in a conformational change and leads to activation through phosphorylation by CAMKK1 (By similarity). Mainly expressed in brain with small amounts in skeletal muscles, kidney, spleen and liver. Strongly expressed in forebrain neocortex, striatum and limbic system. The autoinhibitory domain overlaps with the calmodulin binding region and interacts in the inactive folded state with the catalytic domain as a pseudosubstrate. May be prenylated on Cys-473. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily.