Fig. 7.

Regulatory crosstalk between cysteine oxidation and other PTMs. A, Redox signals have been implicated in regulating the function of numerous enzymes which affect PTMs such as sumoylation, phosphorylation, acetylation, as well as others. Enzymes that both conjugate and remove PTMs can be affected with redox regulation typically repressing but occasionally enhancing enzyme activity. B, FoxO4 is a paradigm for the crosstalk between cysteine oxidation and other PTMs at the level of a single protein. Cysteine oxidation of FoxO4, via disulfide-mediated interaction with the acetyltransferase p300/CBP, increases acetylation and represses FoxO4 transcriptional activity in a redox-dependent manner (114). FoxO4 is phosphorylated and ubiquitinated as well, however it is not known if these PTMs are redox-regulated.