ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with CRKIP1 (KAPP), CRKIP2 and CRKIP3, three kinase-associated type 2C proteins. By salicylic acid (SA) or by a bacterial pathogen infection. May be regulated by WRKY DNA-binding proteins at the transcriptional level. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. CRK subfamily. Truncated N-terminus.