May regulate transmembrane proteins that bind calcium, calmodulin, or nucleotides. Functionally modulates eag potassium channels; increases eag current and whole-cell conductance. Also regulates autophosphorylation of CaMKII. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with eag. Interacts with CaMKII. Eag recruits CASK to the plasma membrane. During embryogenesis, larval and pupal life, found almost exclusively in the central nervous system. In the adult head found in the lamina, the neuropil of the medulla, lobula, lobula plate and in the central brain. Increases synapse-specific, activity-dependent autophosphorylation of CaMKII Thr-287. In the N-terminal section; belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily. Belongs to the MAGUK family. Probable cloning artifact.