Cytochrome b-245 heavy chain (CYBB) (gp91-phox)

Cytochrome b-245 heavy chain, widely known as gp91-phox or NOX2, is the catalytic, membrane-bound subunit of the NADPH oxidase complex primarily expressed in phagocytic cells such as neutrophils and macrophages [2, 3, 12]. Its fundamental biological role is the generation of superoxide radicals through the transfer of electrons from NADPH to molecular oxygen, a process termed the respiratory burst that is critical for the destruction of engulfed pathogens [3, 5, 18]. Mutations in the CYBB gene, which encodes this protein, result in Chronic Granulomatous Disease (CGD), a primary immunodeficiency characterized by life-threatening infections and granuloma formation [3, 13, 15]. Beyond its role in host defense, overactivation of gp91-phox is a major source of oxidative stress in various pathologies, including cardiovascular diseases, neurodegenerative disorders, and ischemic stroke [1, 7, 17]. Consequently, it is a prominent therapeutic target for inhibitors like gp91ds-tat and small molecules such as GSK2795039, which aim to mitigate tissue damage by modulating reactive oxygen species production [1, 10, 11]. However, therapeutic targeting must balance the reduction of harmful oxidative stress with the preservation of essential immune functions to avoid inducing a CGD-like phenotype [2, 6, 18].

Other names

NOX2Cytochrome b(558) subunit betaCGDAMCBX2GP91-1IMD34CGDX

Inhibition of NADPH oxidase activity by blocking the assembly of cytosolic subunits (p47phox, p67phox) to the membrane-bound cytochrome, competing for the NADPH binding site, or directly inhibiting the catalytic core.