CaM-kinase II (CAMK2) is a prominent kinase in the central nervous system. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Autophosphorylation of CAMK2 plays an important role in the regulation of the kinase activity. CAMK2 is composed of four different chains: alpha, beta, gamma, and delta. The different isoforms assemble into homo- or heteromultimeric holoenzymes composed of 8 to 12 subunits (By similarity). Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily.