Fig. 1.

NADPH oxidase/NOX2 activation in intact cells. The active phagocyte NADPH oxidase is a multicomponent enzyme complex composed of six proteins: p22phox (phox: phagocyte oxidase), gp91phox/NOX2, p47phox, p67phox, p40phox and the small G-protein Rac1 or Rac2. In resting cells p47phox, p67phox, p40phox and Rac1/2 are localized in the cytosol, and p22phox and gp91phox are at the plasma membrane and membranes of specific granules to form flavocytochrome b₅₅₈. When cells are activated by a receptor-dependent agonist, the cytosolic components are phosphorylated and migrate to the membranes, where they associate with the membrane-bound components to assemble the catalytically active oxidase (FRO=ROS)