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PDIb family, ERp72 subfamily, first redox inactive TRX-like domain b; ERp72 exhibits both disulfide oxidase and reductase functions like PDI, by catalyzing the formation of disulfide bonds of newly synthesized polypeptides in the ER and acting as isomerases to correct any non-native disulfide bonds. It also displays chaperone activity to prevent protein aggregation and facilitate the folding of newly synthesized proteins. ERp72 contains three redox-active TRX (a) domains and two redox inactive TRX-like (b) domains. Its molecular structure is a"abb'a', compared to the abb'a' structure of PDI. ERp72 associates with several ER chaperones and folding factors to form complexes in the ER that bind nascent proteins. Similar to PDI, the b domain of ERp72 is likely involved in binding to substrates.
Jiyao W et al.(2023). "The conserved domain database in 2023.",