Can phosphorylate the myelin basic protein in vitro (PubMed:14720124). Required for endosperm development in embryos (PubMed:15634699). Maybe involved in auxin and osmotic stress responses (PubMed:21431781). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Uses manganese ion preferentially to magnesium ion. Not stimulated by calmodulin (CaM). Binds calmodulin (CaM) in a calcium-dependent manner. Interacts with CAM1, but not with CAM8. Expressed in reproductive and vegetative tissues, with higher levels in seedlings and flowers, but not in leaves. Induced after P.brassicae oviposition. Calmodulin (CaM)-independent autophosphorylation. Endosperm development arrested at one-cell zygotic stage (PubMed:15634699). Increased resistance to auxin (e.g. IAA and NPA) and osmotic stress (e.g. mannitol) (PubMed:21431781). Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.