Multiple Functions and Regulation of Mammalian Peroxiredoxins

Peroxiredoxins (Prxs) constitute a major family of peroxidases, with mammalian cells expressing six Prx isoforms (PrxI to PrxVI). Cells produce hydrogen peroxide (H 2 O 2 ) at various intracellular locations where it can serve as a signaling molecule. Given that Prxs are abundant and possess a structure that renders the cysteine (Cys) residue at the active site highly sensitive to oxidation by H 2 O 2 , the signaling function of this oxidant requires extensive and highly localized regulation. Recent findings on the reversible regulation of PrxI through phosphorylation at the centrosome and on the hyperoxidation of the Cys at the active site of PrxIII in mitochondria are described in this review as examples of such local regulation of H 2 O 2 signaling. Moreover, their high affinity for and sensitivity to oxidation by H 2 O 2 confer on Prxs the ability to serve as sensors and transducers of H 2 O 2 signaling through transfer of their oxidation state to bound effector proteins.