NADPH-oxidase (Nox) is a highly regulated dynamic complex comprising membrane and cytosolic proteins and is the major source of nonmitochondrial cellular reactive oxygen species (ROS). In phagocyte cells, in which ROS are produced in huge amounts, Nox is "naturally" assailed by the action of its own ROS. We have subjected each individual component of Nox or the whole complex at various times during the assembly process either to oxygen free radicals produced by radiolysis or to hydrogen peroxide. Membrane components presented the highest irradiation sensitivity. Irradiation of p67(phox) drastically decreased its interaction with arachidonic acid and destabilized the [p47(phox)-p67(phox)] complex. When the system was irradiated during its assembly process, we could identify an initial irradiation-sensitive phase followed by a resistant form when the complex was assembled.
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