H2S signalling through protein sulfhydration and beyond

Hydrogen sulfide (H2S) has recently emerged as a mammalian gaseous messenger molecule, akin to nitric oxide and carbon monoxide. H2S is predominantly formed from Cys or its derivatives by the enzymes cystathionine beta-synthase and cystathionine gamma-lyase. One of the mechanisms by which H2S signals is by sulfhydration of reactive Cys residues in target proteins. Although analogous to protein nitrosylation, sulfhydration is substantially more prevalent and usually increases the catalytic activity of targeted proteins. Physiological actions of sulfhydration include the regulation of inflammation and endoplasmic reticulum stress signalling as well as of vascular tension.