ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Mostly expressed in flower buds, and, to a lower extent, in inflorescence bolts, roots, seedlings, leaves and siliques. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.