Glutathione peroxidases (Gpxs) are the key anti-oxidant enzymes found in Saccharomyces cerevisiae. Among the three Gpx isoforms, glutathione peroxidase 3 (Gpx3) is ubiquitously expressed and modulates the activities of redox-sensitive thiol proteins involved in various biologi-cal reactions. By using a proteomic approach, glyceralde-hyde-3-phosphate dehydrogenase 2 (GAPDH2; EC 1.2.1.12) was found as a candidate protein for interaction with Gpx3. GAPDH, a key enzyme in glycolysis, is a multi-functional protein with multiple intracellular localizations and diverse activities. To validate the interaction between Gpx3 and GAPDH2, immunoprecipitation and a pull-down assay were carried out. The results clearly showed that GAPDH2 interacts with Gpx3 through its carboxyl-terminal domain both in vitro and in vivo. Additionally, Gpx3 helps to reduce the S-nitrosylation of GAPDH upon nitric oxide (NO) stress; this subsequently increases cellular viability. On the basis of our findings, we suggest that Gpx3 protects GAPDH from NO stress and thereby contributes to the maintenance of homeostasis during exposure to NO stress.

Keywords: Apoptosis, GAPDH, glutathione peroxidase 3, nitosylation, NO stress