Autodegradation of protein disulfide isomerase

Protein disulfide isomerase (PDI) and its degradation products were found i n HepG2, COS-1, and CHO-K1 cells. Whether or not the products were formed t hrough autodegradation of PDI was examined, since PDI contains the CGHC mot if, which is the active center of proteolytic activity in ER-60 protease. C ommercial bovine PDI was autodegraded to produce a trimmed PDI. In addition , human recombinant PDI also had autodegradation activity. Mutant recombina nt PDIs with CGHC motifs of which cysteine residues were replaced with seri ne or alanine residues were prepared. However, they were not autodegraded, suggesting the cysteine residues of motifs are necessary for autodegradatio n.