The multifunctional CAMK2, or Ca2+/calmodulin-dependent protein kinase II, is a well known effector of calcium- and calmodulin- mediated functions. It is present in many tissues but is most abundant in the brain. 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. Autophosphorylation plays an important role in the regulation of the kinase activity. CAMK2 is required for synaptic plasticity, as in Long Term Potentiation (LTP), a cellular model for learning and memory. 
CAMK2B is the beta chain. There are seven named isoforms produced by alternative splicing. The variable region of the CAMK2B protein is encoded by at least 7 exons (V1 to V7). Alternative splicing within this region gives rise to CAMK2B isoforms.CAMK2G is the gamma chain. CAMK2G has six alternatively spliced variants that encode six different isoforms. Some of these variants have been identified in human tumors.