Occurs in almost all aerobically respiring organisms and serves to protect cells from the toxic effects of hydrogen peroxide. 2 H2O2 = 2 H2O + O2 Homotetramer and heterotetramer. At least six or seven isozymes are produced from a mixture of 3 gene products. Interacts with NCA1 (PubMed:25700484). Interacts with LSD1 (PubMed:23958864). By hydrogen peroxide. By abscisic acid (ABA), drought, and salt stress through the MKK1-MPK6 mediation. Belongs to the catalase family.