A key regulator of plasticity in synaptic physiology and behavior, alterations in its activity produce pleiotrophic effects that involve synaptic transmission and development as well as various aspects of behavior. Directly modulates eag potassium channels. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] CASK plays a role in regulation of CaMKII autophosphorylation. When complexed with CASK and in the presence Ca[2+]/CaM, autophosphorylation of Thr-287 causes constitutive activation of the kinase. In the absence of Ca[2+]/CaM, autophosphorylation of Thr-306 causes inactivation of the kinase. Interacts with CASK. Expressed at a high level in the central nervous system during the late embryonic stage. In adults, expression is more abundant in the head than in the body. Autophosphorylation at Thr-287 is independent of autophosphorylation at Thr-306 and Thr-307. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily. Calmodulin-dependent kinase entry