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 (PubMed:29581216). 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 (PubMed:19825577). Mainly expressed in young roots, and, to a lower extent, in leaf veins, seedlings, stems, leaf sheath and young spikelet (PubMed:29581216). By cold and dehydration (PubMed:19825577). Induced by salt (NaCl) and oxidative (H(2)O(2)) stresses (PubMed:29581216, PubMed:19825577). Palmitoylated. Autophosphorylated. Increased sensitivity to salt (NaCl) stress with increased oxidative attack on membrane lipids and higher intracellular Na(+)/K(+) ratio associated with reduced phosphorylation of CATC. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.