Activation of the neutrophil respiratory burst oxidase.

The neutrophil respiratory burst oxidase is a multicomponent activatable enzyme comprising one of the major phagocyte antimicrobial systems. In the genetic disorder chronic granulomatous disease, absent oxidase function is associated with recurrent, severe, and often life-threatening infections. The components of the oxidase system include both membrane-bound and soluble cytosolic proteins. A primary feature of stimulus-dependent activation is the translocation of a complex of cytosolic factors to the membrane, where they associate with a flavocytochrome enzyme. Interactions among the various oxidase components occur through a number of specific regions, including SH3 domains and proline-rich motifs. The fully assembled complex functions as an electron transport system, moving electrons from cytosolic NADPH to molecular oxygen to form superoxide, which, along with subsequent reactive products, exerts microbicidal and cytotoxic activities.