PDIa family, N-terminal ERdj5 subfamily; ERdj5, also known as JPDI and macrothioredoxin, is a protein containing an N-terminal DnaJ domain and four redox active TRX domains. This subfamily is comprised of the first TRX domain of ERdj5 located after the DnaJ domain at the N-terminal half of the protein. ERdj5 is a ubiquitous protein localized in the endoplasmic reticulum (ER) and is abundant in secretory cells. It's transcription is induced during ER stress. It interacts with BiP through its DnaJ domain in an ATP-dependent manner. BiP, an ER-resident member of the Hsp70 chaperone family, functions in ER-associated degradation and protein translocation.