Serine/threonine-protein kinase with low activity. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Homodimer. Expressed in roots, leaves, shoot apical meristems (SAM), and floral buds. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Sequencing errors.