The mammalian cytosolic thioredoxin reductase pathway acts via a membrane 1 protein to reduce ER-localised proteins

Autor: Cao, Xiaofei, Lilla, Sergio, Cao, Zhenbo, Pringle, Marie Anne, Oka, Ojore B.V., Robinson, Philip J., Szmaja, Tomasz, Van Lith, Marcel, Zanivan, Sara, Bulleid, Neil
Jazyk: angličtina
Rok vydání: 2020
ISSN: 0021-9533
Popis: Folding of proteins entering the mammalian secretory pathway requires the insertion of the correct disulfides. Disulfide formation involves both an oxidative pathway for their insertion and a reductive pathway to remove incorrectly formed disulfides. Reduction of these disulfides is critical for correct folding and degradation of misfolded proteins. Previously, we showed that the reductive pathway is driven by NADPH generated in the cytosol. Here, by reconstituting the pathway using purified proteins and ER microsomal membranes, we demonstrate that the thioredoxin reductase system provides the minimal cytosolic components required for reducing proteins within the ER lumen. In particular, saturation of the pathway and its protease sensitivity demonstrates the requirement for a membrane protein to shuttle electrons from the cytosol to the ER. These results provide compelling evidence for the critical role of the cytosol in regulating ER redox homeostasis ensuring correct protein folding and facilitating the degradation of misfolded ER proteins.
Databáze: OpenAIRE