ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] A number of isoforms are produced. According to EST sequences. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Extended C-terminus. Extended C-terminus.