Constitutive NADPH oxidase which generates superoxide intracellularly upon formation of a complex with CYBA/p22phox. Regulates signaling cascades probably through phosphatases inhibition. May function as an oxygen sensor regulating the KCNK3/TASK-1 potassium channel and HIF1A activity. May regulate insulin signaling cascade. May play a role in apoptosis, bone resorption and lipolysaccharide-mediated activation of NFKB. Activated by insulin. Inhibited by diphenylene iodonium (By similarity). Inhibited by plumbagin. Activated by phorbol 12-myristate 13-acetate (PMA). Interacts with, relocalizes and stabilizes CYBA/p22phox. Interacts with TLR4. Interacts with protein disulfide isomerase (By similarity). Interacts with PPP1R15A (By similarity). May localize to plasma membrane and focal adhesions. EXpressed in brain, in all layers of the cerebellum, in pyramidal cells of the Ammon horn and in Purkinje cells (at protein level). Expressed in osteoclasts, leukocytes, kidney, liver and lung. Upon brain ischemia it is up-regulated in ischemic tissues and more specially in neocapillaries (at protein level). Up-regulated upon hypoxia. N-glycosylation is required for the function.