Protein disulfide isomerase (PDI) is a multifunctional protein that catalyzes the formation, breakage and rearrangement of disulfide bonds. At the cell surface, the protein seems to act as a reductase that cleaves disulfide bonds of proteins attached to the cell. It may therefore cause structural modifications of exofacial proteins. Inside the cell, PDI seems to form/rearrange disulfide bonds of nascent proteins. At high concentrations, it functions as a chaperone that inhibits aggregation of misfolded proteins. At low concentrations, it facilitates aggregation (anti-chaperone activity). PDI may be involved with other chaperones in the structural modification of the TG precursor in hormone biogenesis. It also acts a structural subunit of various enzymes such as prolyl 4-hydroxylase and microsomal triacylglycerol transfer protein MTTP. Receptor for LGALS9; the interaction retains P4HB at the cell surface of Th2 T helper cells, increasing disulfide reductase activity at the plasma membrane, altering the plasma membrane redox state and enhancing cell migration.
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Protein Aliases: CaO19.12595; Cellular thyroid hormone-binding protein; collagen prolyl 4-hydroxylase beta; Endoplasmic reticulum resident protein 59; Eps1p; ER protein 59; glutathione-insulin transhydrogenase; p55; PDI; PDI1P; procollagen-proline, 2-oxoglutarate 4-dioxygenase (proline 4-hydroxylase), beta polypeptide; Prolyl 4-hydroxylase subunit beta; prolyl 4-hydroxylase, beta polypeptide; protein disulfide isomerase; Protein disulfide isomerase (Prolyl 4-hydroxylase, beta polypeptide); protein disulfide isomerase family A, member 1; protein disulfide isomerase-associated 1; protein disulfide isomerase/oxidoreductase; Protein disulfide-isomerase; protocollagen hydroxylase; testicular secretory protein Li 32; thyroid hormone-binding protein p55
Gene Aliases: CLCRP1; DSI; ERBA2L; ERp59; GIT; P4HB; P4Hbeta; PDI; PDIA1; PDIR; PHDB; PO4DB; PO4HB; PROHB; Thbp
Molecular Function: chaperone