Important in cellular regulation. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Multimeric. Present with 1520 molecules/cell in log phase SD medium. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. CaMK subfamily.