Figure 4.

Two cysteine residues are responsible for the regulation of some target proteins by S‐sulfuration. The cys422 and cys634 at the amino terminus of TRPA1 channels are sensitive to H₂S_n to induce Ca²⁺ influx (Hatakeyama et al., 2015; Kimura et al., 2013). Either one of the cysteine residues is S‐sulfurated to react with the remaining thiol to produce a cysteine disulfide bond, which may induce enough conformational changes to modify their activity. Alternatively, both cysteine residues are equally S‐sulfurated. However, compared with the formation of a disulfide bond, it may induce less conformational change to regulate the activity of the channels. When either the cys71 or cys124 of PTEN is S‐sulfurated, a cysteine disulfide bond is produced that then inactivates its activity (Greiner et al., 2013). A dimer formation by each cysteine residue of the monomer protein kinase G1α (PKG1α) activates the enzyme (Stubbert et al., 2014)