Protein Disulfide Isomerase 2BJX

Protein disulfide isomerase (PDI) is a multifunctional protein of the endoplasmic reticulum, which catalyzes the formation, breakage and rearrangement of disulfide bonds during protein folding. It consists of four domains designated a, b, b and a. Both a and a domains contains an active site with the sequence motif -Cys-Gly-His-Cys-involved directly in thiol-disulfide exchange reactions. As expected these domains have structures very similar to the ubiquitous redox protein thioredoxin. A low-resolution NMR structure of the b domain revealed that this domain adopts a fold similar to the PDI a domain and thioredoxin [Kemmink, J., Darby, N.J., Dijkstra, K., Nilges, M. and Creighton, T.E. (1997) Curr. Biol. 7, 239-245]. A refined ensemble of solution structures based on the input of 1865 structural restraints shows that the structure of PDI b is well defined throughout the complete protein except for about 10 residues at the C-terminus of the sequence. 15N relaxation data show that these r