NUCLEAR-MAGNETIC-RESONANCE CHARACTERIZATION OF THE N-TERMINAL THIOREDOXIN-LIKE DOMAIN OF PROTEIN DISULFIDE-ISOMERASE

A genetically engineered protein consisting of the 120 residues at the N-terminus of human protein disulfide isomerase (PDI) has been characterized by H-1, C-13, and N-15 NMR methods. The sequence of this protein is 35% identical to Escherichia coli thioredoxin, and it has been found also to have similar patterns of secondary structure and beta-sheet topology. The results confirm that PDI is a modular, multidomain protein. The last 20 residues of the N-terminal domain of PDI are some of those that are similar to part of the estrogen receptor, yet they appear to be an intrinsic part of the thioredoxin fold. This observation makes it unlikely that any of the segments of PDI with similarities to the estrogen receptor comprise individual domains.