2. Academic Validation
  3. SLC33A1 exports oxidized glutathione to maintain endoplasmic reticulum redox homeostasis

SLC33A1 exports oxidized glutathione to maintain endoplasmic reticulum redox homeostasis

  • bioRxiv. 2026 Mar 16:2026.02.01.703113. doi: 10.64898/2026.02.01.703113.
Shanshan Liu 1,  Mark Gad 1 2,  Caifan Li 1,  Kevin Cho 3 4 5 6,  Yuyang Liu 1,  Khando Wangdu 1,  Viktor Belay 2 7 8,  Alon Millet 9,  Hiroyuki Kojima 10,  Henry Sanford 10,  Michele Wölk 11,  Linas Urnavicius 12,  Maria Fedorova 11,  Gary J Patti 3 4 5 6,  Ekaterina V Vinogradova 10,  Richard K Hite 2,  Kıvanç Birsoy 1
Affiliations

Affiliations

  • 1 Laboratory of Metabolic Regulation and Genetics, The Rockefeller University, New York, NY, USA.
  • 2 Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, USA.
  • 3 Department of Chemistry, Washington University, St Louis, MO, USA.
  • 4 Center for Mass Spectrometry and Metabolic Tracing, Washington University, St Louis, MO, USA.
  • 5 Siteman Cancer Center, Washington University School of Medicine, St Louis, MO, USA.
  • 6 Center for Human Nutrition, Department of Medicine, Washington University School of Medicine, St Louis, MO, USA.
  • 7 Physiology, Biophysics, and Systems Biology (PBSB) Program, Weill Cornell Graduate School of Biomedical Sciences, New York, NY, USA.
  • 8 Computational and Systems Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
  • 9 Laboratory of Systems Cancer Biology, The Rockefeller University, New York, NY, USA.
  • 10 Laboratory of Chemical Immunology and Proteomics, The Rockefeller University, New York, NY, USA.
  • 11 Center of Membrane Biochemistry and Lipid Research, University Hospital and Faculty of Medicine Carl Gustav Carus of Dresden University of Technology, Dresden, Germany.
  • 12 Laboratory of Chemistry and Cell Biology, The Rockefeller University, New York, NY, USA.
PMID: 41676593 DOI: 10.64898/2026.02.01.703113
Abstract

The endoplasmic reticulum (ER) requires an oxidative environment to support the efficient maturation of secretory and membrane proteins. This is in part established by glutathione, a redox-active metabolite present in reduced (GSH) and oxidized (GSSG) forms. The ER maintains a higher GSSG:GSH ratio than the cytosol; however, the mechanisms controlling ER redox balance remain poorly understood. To address this, we developed a method for the rapid immunopurification of the ER, enabling comprehensive profiling of its proteome and metabolome. Combining this approach with CRISPR screening, we identified SLC33A1 as the major ER GSSG exporter in mammalian cells. Loss of SLC33A1 leads to GSSG accumulation in the ER and a liposome-based assay demonstrates that SLC33A1 directly transports GSSG. Cryo-EM structures and molecular dynamics simulations reveal how SLC33A1 binds GSSG and identify residues critical for its transport. Finally, an imbalance in GSSG:GSH ratio induces ER stress and dependency on the ER-associated degradation (ERAD) pathway, driven by a shift in protein disulfide isomerases (PDIs) toward their oxidized forms. Altogether, our work establishes SLC33A1-mediated GSSG export as a key mechanism for ER redox homeostasis and protein maturation.

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