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 charac terized by H-1, C-13, and N-15 NMR methods. The sequence of this prote in is 35% identical to Escherichia coli thioredoxin, and it has been f ound also to have similar patterns of secondary structure and beta-she et topology. The results confirm that PDI is a modular, multidomain pr otein. The last 20 residues of the N-terminal domain of PDI are some o f those that are similar to part of the estrogen receptor, yet they ap pear to be an intrinsic part of the thioredoxin fold. This observation makes it unlikely that any of the segments of PDI with similarities t o the estrogen receptor comprise individual domains.