ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Highly expressed in most normal human tissues, with an exception of in testis, small intestine, colon and peripheral blood leukocyte. Belongs to the protein kinase superfamily. AGC Ser/Thr protein kinase family.