NADPH Oxidase 1 and Its Derived Reactive Oxygen Species Mediated Tissue Injury and Repair

Figure 1

Structural differences among mammalian Nox homologues. Nox1–5 share six highly conserved transmembrane domains, while Duox1 and Duox2 have an additional N-terminal transmembrane domain. Four conserved histidines that bind two hemes between the third and fifth (fourth and sixth in Duox) of the transmembrane domains provide an oxygen binding site. The cytoplasmic C-terminus contains domans for binding of the substrate NADPH and the cofactor FAD. An additional N-terminal extension containing Ca²⁺-binding EF hands exists in both Nox5 and Duox, allowing for Ca²⁺ activation. Duox also has an extracellular peroxidase homology domain at the N-terminus.