FIG. 5.

Schematic representation of the t-PMET. At the cytosolic side of the plasma membrane, a quinone reductase is present that reduces CoQ to ubiquinol (CoQH₂). CoQH₂ shuttles the electrons to the NOX that is able to reduce extracellular ascorbyl radicals (Asc^•) produce superoxide (O₂^•−), reduce O₂ to water, and reduce protein disulfides. CoQ, Coenzyme Q; NOX, NADPH oxidase; t-PMET, trans-plasma membrane electron transport. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars