Acts probably as a dual specificity protein kinase (Probable). Regulates hydrogen peroxide (H(2)O(2)) homeostasis and improves salt tolerance by phosphorylating tyrosine residues of CATC thus activating its catalase activity. Promotes growth at the seedling stage and prevents grain yield loss under salt stress conditions (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Self-interacts. Interacts with CATA, CATB and CATC at the plasma membrane. Accumulates in seeds. By cold, salt and dehydration. Palmitoylated. Autophosphorylated. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.