biostudies-literatureUnknown299(11)Cai XEndoplasmic reticulum (ER)-associated degradation (ERAD) is a protein quality control process that eliminates misfolded proteins from the ER. DnaJ homolog subfamily C member 10 (ERdj5) is a protein disulfide isomerase family member that accelerates ERAD by reducing disulfide bonds of aberrant proteins with the help of an ER-resident chaperone BiP. However, the detailed mechanisms by which ERdj5 acts in concert with BiP are poorly understood. In this study, we reconstituted an in vitro system that monitors ERdj5-mediated reduction of disulfide-linked J-chain oligomers, known to be physiological ERAD substrates. Biochemical analyses using purified proteins revealed that J-chain oligomers were reduced to monomers by ERdj5 in a stepwise manner via trimeric and dimeric intermediates, and BiP syThe Journal of biological chemistry105274https://www.ebi.ac.uk/biostudies/studies/S-EPMC10591012biostudies-literatureMechanistic characterization of disulfide bond reduction of an ERAD substrate mediated by cooperation between ERdj5 and BiP.PMC10591012Kato YInaba KInoue MIto SNoi KNagata KCai XUshioda RfalseMechanistic characterization of disulfide bond reduction of an ERAD substrate mediated by cooperation between ERdj5 and BiP.Endoplasmic reticulum (ER)-associated degradation (ERAD) is a protein quality control process that eliminates misfolded proteins from the ER. DnaJ homolog subfamily C member 10 (ERdj5) is a protein disulfide isomerase family member that accelerates ERAD by reducing disulfide bonds of aberrant proteins with the help of an ER-resident chaperone BiP. However, the detailed mechanisms by which ERdj5 acts in concert with BiP are poorly understood. In this study, we reconstituted an in vitro system that monitors ERdj5-mediated reduction of disulfide-linked J-chain oligomers, known to be physiological ERAD substrates. Biochemical analyses using purified proteins revealed that J-chain oligomers were reduced to monomers by ERdj5 in a stepwise manner via trimeric and dimeric intermediates, and BiP sy2023-01-01T00:00:00Z2023 Nov2026-05-28T16:18:05.441Z2025-04-05T11:47:47.751ZS-EPMC105910123773903710.1016/j.jbc.2023.105274