Protein Disulfide Isomerase: Structure, Mechanism of Oxidative Protein Folding and Multiple Functional Roles

Protein disulfide isomerase (PDI) is a member of the thioredoxin superfamily of redox proteins. Originally, PDI was identified in the lumen of the endoplasmic reticulum and subsequently detected abundantly in many other tissues and account for 0.8% of total cellular protein. PDI consists of four tandem thioredoxin-like domains a, b, b′, and a′ plus a C-terminal extension which are arranged into a U-shape structure. PDI has three catalytic activities including, thiol-disulfide oxidoreductase, disulfide isomerase and redox-dependent chaperone. Now the functions ascribed to PDI have evolved significantly because recent studies have shown that it has detrimental as well as protective effects in diseases states. Keeping the above views in mind, in this review we have discussed the structure of PDI, its catalytic and chaperone activity and its role in various diseases states.