Figure 2.

Possible ways of redox signal spreading — from left to right: (i) direct superoxide diffusion; (ii) direct H₂O₂ diffusion; (iii) peroxiredoxin-mediated redox signal transfer including diffusion of peroxiredoxin decamers; (iv) combination of (ii) and (iii), i.e., H₂O₂ diffusion followed by the peroxiredoxin relay (peroxiredoxin “redox kiss”); and (v) hypothetical redox relay via an array of peroxiredoxins. Note, that according to a flood-gate model, H₂O₂ oxidizes PRDX to higher states than a sulfenic state (green; basic reduced state light green), such as sulfinic (yellow) and irreversible sulfonic state (orange). This allows only distant decamers in a sulfenic state either to migrate to the target (iii) or to oxidize target at its vicinity (iv). The hypothetical mechanism (v) should still be verified experimentally.