Fig 4. Schematic illustration of electron transfer in NOX1.

The electrons are donated by an NADPH at the NADPH interacting domain of NOX1. A FAD molecule then accepts the two electrons released from the NADPH molecule, and is reduced to FADH₂, which further passes two electrons on to the transmembrane heme groups. The electrons are then transported through the 6-TM loop region towards the extracellular part of NOX1. The extracellular region provides a harbor for the final step of ROS generation, where two oxygen molecules encounter two electrons released by the outer-heme group and are reduced into the free radical form of O₂^•−.