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Abstract
Despite its toxicity, H(2)O(2) is produced as a signaling molecule that oxidizes critical
cysteine residues of effectors such as protein tyrosine phosphatases in response to
activation of cell surface receptors. It has remained unclear, however, how H(2)O(2)
concentrations above the threshold required to modify effectors are achieved in the
presence of the abundant detoxification enzymes peroxiredoxin (Prx) I and II. We now
show that PrxI associated with membranes is transiently phosphorylated on tyrosine-194
and thereby inactivated both in cells stimulated via growth factor or immune receptors
in vitro and in those at the margin of healing cutaneous wounds in mice. The localized
inactivation of PrxI allows for the transient accumulation of H(2)O(2) around membranes,
where signaling components are concentrated, while preventing the toxic accumulation
of H(2)O(2) elsewhere. In contrast, PrxII was inactivated not by phosphorylation but
rather by hyperoxidation of its catalytic cysteine during sustained oxidative stress.
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