Collagen propeptides and chains Collagen propeptides and chains:P4HB PDI is a chaperone for collagen peptides As the collagen peptide chain is translocated across the membrane of the endoplasmic reticulum, intrachain disulfide bonds are formed within the N- and C-propeptides. This allows the triple helical domain to form a nucleation point at its C-terminal end and ensures correct alignment of the chains (Engel & Prockop 1991). Protein disulfide isomerase (P4HB) catalyzes the formation of both intra- (Bulleid & Freedman 1988) and inter-chain disulfide bonds (Koivu & Myllylä 1987). In addition, PDI acts as a molecular chaperone, interacting with monomeric collagen propeptide chains to prevent premature assembly or aggregation (Wilson et al. 1998). Authored: Jupe, S, 2010-07-20 Edited: Jupe, S, 2012-05-14 Pubmed1867713 Pubmed3173483 Pubmed3571251 Pubmed9545296 Pubmed9560306 Reactome Database ID Release 432002460 Reactome, http://www.reactome.org ReactomeREACT_120881 Reviewed: Canty-Laird, EG, 2012-05-24