Phosphorylates PPP1C, phosphorylase b and CFTR. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with PPP1C and inhibitor-2. Mainly expressed in brain, especially in the olfactory bulb, olfactory tubercle, hippocampus, striatum, cerebellum and cerebral cortex. Weakly expressed in skeletal muscle and not expressed in liver. Expression observed during all tested stages from 18 dpc to postnatal week 6, but it was especially high during the early postnatal stage (postnatal weeks 0-2). Autophosphorylated. Phosphorylated (By similarity). Belongs to the protein kinase superfamily. Tyr protein kinase family.