Identification of the redox partners of ERdj5/JPDI, a PDI family member, from an animal tissue

•A simple strategy stabilized disulfide-linked complexes formed in mouse tissues.•ERdj5, a PDI family member, and its mixed-disulfides were abundant in the epididymis.•A number of presumable redox partners of ERdj5 were identified from this tissue.•PDI and ERp72 were the redox partners of ERdj5 in the tissue.•Genetic engineering was not required for the identification of the redox partners. ERdj5 (also known as JPDI) is a member of PDI family conserved in higher eukaryotes. This protein possesses an N-terminal J domain and C-terminal four thioredoxin domains each having a redox active site motif. Despite the insights obtained at the cellular level on ERdj5, the role of this protein in vivo is still unclear. Here, we present a simple method to purify and identify the disulfide-linked complexes of this protein efficiently from a mouse tissue. By combining acid quenching and thiol-alkylation, we identified a number of potential redox partners of ERdj5 from the mouse epididymis. Further, we show that ERdj5 indeed interacted with two of the identified proteins via formation of intermolecular disulfide bond. Thus, this approach enabled us to detect and identify redox partners of a PDI family member from an animal tissue.