Abstract
The reducing power of glutathione, expressed by its reduction potential EGSH, is an accepted measure for redox conditions in a given cell compartment. In the endoplasmic reticulum (ER), EGSH is less reducing than elsewhere in the cell. However, attempts to determine EGSH(ER) have been inconsistent and based on ineligible assumptions. Using a codon-optimized and evidently glutathione-specific glutaredoxin-coupled redox-sensitive green fluorescent protein (roGFP) variant, we determined EGSH(ER) in HeLa cells as -208±4 mV (at pH 7.0). At variance with existing models, this is not oxidizing enough to maintain the known redox state of protein disulfide isomerase family enzymes. Live-cell microscopy confirmed ER hypo-oxidation upon inhibition of ER Ca(2+) import. Conversely, stressing the ER with a glycosylation inhibitor did not lead to more reducing conditions, as reported for yeast. These results, which for the first time establish the oxidative capacity of glutathione in the ER, illustrate a context-dependent interplay between ER stress and EGSH(ER). The reported development of ER-localized EGSH sensors will enable more targeted in vivo redox analyses in ER-related disorders.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
