InterPro: IPR005982 Thioredoxin reductase

Reactive oxygen species (ROS) are known mediators of intracellular signalling cascades. Excessive production of ROS may, however, lead to oxidative stress, loss of cell function, and ultimately apoptosis or necrosis. A balance between oxidant and antioxidant intracellular systems is hence vital for cell function, regulation, and adaptation to diverse growth conditions. Thioredoxin reductase in conjunction with thioredoxin is a ubiquitous oxidoreductase system with antioxidant and redox regulatory roles. Thioredoxin reductase (EC:1.8.1.9) reduces oxidised thioredoxin in the presence of NADPH. Reduced thioredoxin serves as an electron donor for thioredoxin peroxidase which consequently reduces H₂O₂ to H₂O. In mammals, extracellular forms of Trx also have cytokine-like effects. Mammalian TrxR has a highly reactive active site selenocysteine residue resulting in a profound reductive capacity, reducing several substrates in addition to Trx [1].