Fig. 2
From: NADPH oxidase in brain injury and neurodegenerative disorders
NOX isoforms and regulatory subunits. NADPH oxidases have a primary role to generate ROS. Several components and domains make up the transmembrane active enzyme complexes of NADPH oxidase isoforms. NOX1-5 and DUOX1/DUOX2 are shown here. Upon activation, an electron will be transferred from NADPH to O2 to form superoxide. NOX4 generated superoxide undergoes rapid conversion into hydrogen peroxide, which mediates many of its downstream effects. NOX5 and the DUOX enzymes are sensitive to cellular Ca2+ concentrations