Receptor kinase that detects X.oryzae pv. oryzae protein Ax21 to promote innate immunity (PubMed:20118235). Following X.oryzae pv. oryzae protein Ax21 detection, undergoes cleavage, releasing the processed protein kinase Xa21 chain (By similarity). The processed protein kinase Xa21 chain released by protein cleavage after X.oryzae pv. oryzae protein Ax21 detection translocates into the nucleus where it can bind and regulate WRKY62, a transcription factor (By similarity). Confers resistance to the bacterial pathogen X.oryzae pv. oryzae (Xoo) (PubMed:8525370, PubMed:19825552, PubMed:20118235). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Enzymatic activity is fifteen time stronger with Mn(2+) than with Mg(2+). Binds to XB3, XB15 and XB24 (PubMed:20118235). Receptor kinase-like protein Xa21, processed: Interacts with WRKY62/XB10 in the nucleus (PubMed:19825552, PubMed:20118235). Present in cortical and perinuclear endoplasmic reticulum. Cleaved upon X.oryzae pv. oryzae protein Ax21 recognition; the kinase containing fragment is translocated into the nucleus. Undergoes protein cleavage upon X.oryzae pv. oryzae protein Ax21 detection, thus releasing the processed protein kinase Xa21 chain. Autophosphorylated on serine and threonine residues; these phosphorylation prevents proteolytic degradation. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.