Potent and specific cellular inhibitor of CaM-kinase II (CAMK2) (PubMed:9724800, PubMed:17942605). Traps Ca(2+)/calmodulin on CAMK2 (PubMed:17942605). Interacts with CAMK2A and CAMK2B in the presence of Ca(2+)/calmodulin or after autophosphorylation. Excluded from nucleus when coexpressed with activated CAMK2. Expressed in forebrain, hippocampus, midbrain, cerebellum, and testis. Expressed in forebrain, hippocampus, midbrain, and cerebellum (at protein level). In the cortex expressed more in laminae II and III than in laminae IV-VI. Expressed within the pyramidal layer of the hippocampus and granular layer of the dentate gyrus as well as in the olfactory bulb. Diffusely expressed within the caudate-putamen and globus pallidus. Diffusely expressed throughout regions of the midbrain. In cerebellum, expressed within the Purkinje and granular layer. Stronger expressed in the cerebellum. Highly expressed in frontal cortex, hippocampus, olfactory bulb, caudate-putamen and cerebellum exhibit (at protein level). Belongs to the CAMK2N family.