Affinage

PDIA2

Protein disulfide-isomerase A2 · UniProt Q13087

Length
525 aa
Mass
58.2 kDa
Annotated
2026-06-10
20 papers in source corpus 15 papers cited in narrative 15 extracted findings
Cross-family judge vs UniProt: Affinage preferred faithfulness: 7/7 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

PDIA2 (PDIp) is a pancreas-enriched, ER-resident protein disulfide isomerase that catalyzes thiol-disulfide exchange to assist folding of secretory proteins, particularly pancreatic digestive enzymes (PMID:8561901, PMID:30315102). It carries two thioredoxin-like active sites and an ER retention signal, and reconstituted recombinant protein catalyzes reductive cleavage of insulin and renaturation of reduced RNaseA (PMID:8561901). Beyond its catalytic role, PDIA2 acts as a molecular chaperone independently of its isomerase activity: alkylation or mutation of active-site cysteines abolishes enzymatic function while preserving the ability to form stable, stoichiometric complexes with denatured substrates and to prevent aggregation, an activity retained by the active-site-free b-b' fragment (PMID:20423326). It recognizes substrates through exposed aromatic (tyrosine/tryptophan) and hydroxyaryl motifs (PMID:10794419, PMID:11237859), and in vivo it physically engages multiple pancreatic digestive enzymes, preventing proelastase aggregation and enhancing secretion of activatable, properly folded enzyme (PMID:30315102). PDIA2 is a glycoprotein whose N-glycosylation (notably at N284) modulates inter-subunit disulfide-bonded dimer formation, and a non-active-site Cys-4 mediates redox-dependent dimerization that exposes hydrophobic patches and enhances chaperone activity under oxidizing conditions (PMID:19150607, PMID:23167757). The hydroxyaryl-binding b-b' domain also binds 17β-estradiol via His278, allowing PDIp to act as a high-capacity intracellular estradiol reservoir in pancreatic tissue that protects bound E2 from metabolic disposition (PMID:19429457, PMID:22747530, PMID:23931275). Under stress, PDIA2 acquires non-canonical localizations and functions: it translocates from the ER to mitochondria in colon cancer to interact with complex I/II components, inhibiting oxidative phosphorylation and promoting glycolysis and tumor growth (PMID:35860571), and it is exported to the cell surface and extracellular vesicles where its isomerase activity activates tissue factor to drive pro-thrombotic signaling and ligand-independent androgen receptor activation via Src in prostate cancer (PMID:38589675).

Mechanistic history

Synthesis pass · year-by-year structured walk · 8 steps
  1. 1996 High

    Established that PDIA2 is a bona fide protein disulfide isomerase, defining its core catalytic identity through its two thioredoxin-like active sites and demonstrated thiol-disulfide exchange activity.

    Evidence Recombinant protein expression with in vitro insulin reductive cleavage and RNaseA renaturation assays

    PMID:8561901

    Open questions at the time
    • Did not identify physiological substrates
    • Tissue-specific expression context not yet defined
  2. 1997 Medium

    Located PDIA2 expression to pancreatic acinar cells as a glycoprotein and showed conservation across species, establishing it as a tissue-restricted secretory-pathway PDI.

    Evidence Western blot with PNGase F deglycosylation, immunohistochemistry, and cross-species detection; cross-linking in dog pancreas microsomes during translocation

    PMID:9115635 PMID:9136904

    Open questions at the time
    • Functional role of glycosylation unresolved
    • Specific secretory substrates not identified
  3. 2001 Medium

    Defined the molecular recognition code for PDIA2 substrate binding, showing that aromatic and hydroxyaryl groups serve as docking motifs and rationalizing later ligand-binding behavior.

    Evidence Cross-linking with radiolabeled peptide variants and competition with non-peptide hydroxyaryl ligands in pancreas microsome extracts

    PMID:10794419 PMID:11237859

    Open questions at the time
    • Did not establish which native proteins these motifs map to
    • Binding-site residues not yet mapped
  4. 2010 High

    Separated PDIA2's chaperone function from its enzymatic activity, demonstrating that aggregation prevention and stress protection persist when active-site cysteines are abolished.

    Evidence Iodoacetamide alkylation, active-site mutagenesis, b-b' fragment expression, in vitro aggregation assays, and E. coli stress-protection assay

    PMID:20423326

    Open questions at the time
    • In-cell relevance of enzyme-independent chaperoning not directly tested
    • Substrate spectrum for chaperone mode undefined
  5. 2012 Medium

    Showed that redox state and N-glycosylation regulate PDIA2 quaternary structure, linking Cys-4 dimerization and N284 glycosylation to modulation of chaperone activity and protein interactions.

    Evidence Redox-dependent dimerization, protease sensitivity and chaperone assays with cysteine mutagenesis; site-directed glycosylation mutants with localization and MHC class I pulldown

    PMID:19150607 PMID:23167757

    Open questions at the time
    • Physiological trigger for dimerization in pancreas not defined
    • Functional significance of MHC class I interaction not pursued
  6. 2013 Medium

    Characterized PDIA2 as a high-capacity intracellular estradiol-binding protein, identifying His278 in the b-b' domain as the binding determinant and establishing a reservoir role in pancreatic tissue.

    Evidence Radioligand E2 binding assays, endogenous protein purification, in vivo ovariectomized rat model, and homology modeling with binding-site mutagenesis

    PMID:19429457 PMID:22747530 PMID:23931275

    Open questions at the time
    • Physiological consequence of pancreatic E2 sequestration on signaling not fully resolved
    • Single-lab assays
  7. 2018 High

    Identified pancreatic digestive enzymes as physiological PDIA2 substrates in vivo, confirming its predicted role in folding and secretion of secretory cargo.

    Evidence Acid-quench/thiol-alkylation substrate trapping with MS from mouse pancreas plus co-expression rescue of proelastase folding and secretion

    PMID:30315102

    Open questions at the time
    • Full substrate repertoire not exhaustively defined
    • In vivo loss-of-function consequences in pancreas not assessed
  8. 2024 Medium

    Revealed non-ER, disease-associated functions of PDIA2, where stress-induced relocalization to mitochondria or to extracellular vesicles reprograms metabolism and activates tissue factor / AR signaling to drive tumor progression.

    Evidence Co-IP with mitochondrial complex I/II, metabolic and xenograft assays in colon cancer; EV isolation, TF activity and isomerase inhibition, Src activation, and AR/FOXA1 ChIP at the PDIA2 promoter in prostate cancer

    PMID:35860571 PMID:38589675

    Open questions at the time
    • Mechanism of ER-to-mitochondria translocation not defined
    • Single-lab reports for each non-canonical function
    • Direct structural confirmation of TF activation by PDIA2 isomerase lacking

Open questions

Synthesis pass · forward-looking unresolved questions
  • How PDIA2 is trafficked out of the ER to mitochondria, plasma membrane, and EVs under stress, and whether its pancreatic folding role and its tumor-associated moonlighting functions are mechanistically connected, remains unresolved.
  • No structure of full-length PDIA2 or its substrate complexes
  • Trafficking determinants for non-ER localization unknown
  • Loss-of-function pancreatic phenotype uncharacterized

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0008289 lipid binding 3 GO:0016853 isomerase activity 3 GO:0044183 protein folding chaperone 2 GO:0140096 catalytic activity, acting on a protein 2 GO:0140313 molecular sequestering activity 2
Localization
GO:0005783 endoplasmic reticulum 3 GO:0005739 mitochondrion 1 GO:0005886 plasma membrane 1
Pathway
R-HSA-392499 Metabolism of proteins 3 R-HSA-1643685 Disease 2
Partners
ARFOXA1TF

Evidence

Reading pass · 15 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
1996 PDIA2 (PDIp) was isolated from human pancreas, characterized as a new PDI family member with two thioredoxin-like active sites (WCGHCQ and WCTHCK) and an ER retention signal (KEEL). Recombinant PDIp catalyzed reductive cleavage of insulin and renaturation of reduced RNaseA, confirming enzymatic protein disulfide isomerase activity. Recombinant protein expression and in vitro enzymatic assays (insulin reductive cleavage, RNaseA renaturation) DNA and cell biology High 8561901
1997 PDIA2 (PDIp) is a glycoprotein expressed specifically in pancreatic acinar cells. Western blot with peptide:N-glycosidase F treatment confirmed glycosylation. The protein is conserved between human and mouse pancreas. Western blot, immunohistochemistry, peptide:N-glycosidase F treatment, cross-species protein detection DNA and cell biology Medium 9115635
1997 Canine PDIA2 (PDIp) is in transient contact with secretory proteins during late stages of co- and posttranslational translocation into pancreas microsomes, sharing this polypeptide-binding/chaperoning activity with PDI. Its concentration in pancreatic microsomes approaches that of PDI and major microsomal molecular chaperones. Cross-linking and identification in dog pancreas microsomes during translocation assays FEBS letters Medium 9136904
2000 Tyrosine and tryptophan residues in peptides are the recognition motifs for binding to PDIA2 (PDIp). PDIp specifically interacts with radiolabeled peptides and misfolded proteins in vitro via these aromatic residues. Cross-linking approach with radiolabeled peptides and peptide variants in crude pancreas microsome extracts Protein science Medium 10794419
2001 A hydroxyaryl group is a structural recognition motif for ligand binding to PDIA2 (PDIp). Simple hydroxyaryl-containing constructs, xenobiotics, and phytoestrogens containing an unmodified hydroxyaryl group efficiently inhibit peptide binding to PDIp. Cross-linking competition assay with non-peptide ligands and structural variants The Biochemical journal Medium 11237859
2009 Human PDIA2 (PDIp) binds 17β-estradiol (E2) with an apparent Kd of ~1.5 µM. Among six PDI homologs tested, only PDIp and PDI showed similar E2 binding affinity, but with distinct preferences for estrogen analogs. PDIp can serve as a high-capacity intracellular E2-binding protein, modulating intracellular E2 concentrations in cultured cells and human pancreatic tissue; PDIp-bound E2 can be released upon a drop in extracellular E2, augmenting estrogen receptor-mediated transcription. Radiolabeled 17β-estradiol binding assay, competition binding with analogs, cell-based E2 concentration measurement The Journal of steroid biochemistry and molecular biology Medium 19429457
2009 PDIA2 (PDIp) forms an inter-subunit disulfide bond (primarily through a non-active-site cysteine-4, unique to human and primate PDIp) under oxidizing conditions, which alters its structure (exposes hydrophobic patches, increases protease sensitivity) and enhances its chaperone activity. The protein exists predominantly as a monomer under reducing conditions. Redox-dependent dimerization assay, protease sensitivity assay, chaperone activity assay under reducing vs. oxidizing conditions, mutagenesis of cysteine residues Archives of biochemistry and biophysics Medium 19150607
2010 The chaperone activity of PDIA2 (PDIp) is independent of its enzymatic (isomerase) activity. Alkylation of active-site cysteines abolishes enzymatic activity but preserves chaperone activity. Mutation of active-site cysteine residues confirms this independence. The b-b' fragment (lacking active sites) retains chaperone activity. PDIp forms stable, stoichiometric complexes with denatured substrate proteins (e.g., GAPDH) that can later dissociate. Expression in E. coli confers protection against heat shock and oxidative stress independently of enzymatic activity. Iodoacetamide alkylation, active-site mutagenesis, fragment expression, in vitro aggregation prevention assay, E. coli stress-protection assay The Biochemical journal High 20423326
2011 Both PDIA2 (PDIp) and PDI can attack native disulfide bonds in thermally-unfolded RNase and form stable disulfide-linked complexes via thiol-disulfide exchange. The N-terminal active site of PDIp is essential for this inactivation of RNase. RNase in the complexes can be released and reactivated in a redox-dependent manner. Thermal unfolding assay, co-incubation with PDI/PDIp, alkylation controls, active-site mutagenesis Biochimica et biophysica acta Medium 21238616
2012 All three predicted N-linked glycosylation sites of human PDIA2 (N127, N284, N516) are glycosylated in human cells. Mutation of N284 to Gln increases formation of a highly stable disulfide-bonded PDIA2 dimer, indicating that N284 glycosylation modulates protein-protein interactions. Both wild-type and N127/284/516Q mutant PDIA2 localize to the ER (but not ERGIC), showing glycosylation does not affect ER localization. PDIA2 was identified as binding to HLA-A,B,C (MHC class I) antigens. Site-directed mutagenesis, enzymatic deglycosylation, subcellular localization imaging in HeLa cells, co-immunoprecipitation/pulldown for MHC class I interaction The FEBS journal Medium 23167757
2012 Endogenous PDIA2 (PDIp) purified from rat and human pancreatic tissues binds E2 with a Kd of ~150 nM. PDIp-bound E2 accounts for over 80% of total protein-bound E2 in rat and human pancreatic tissue. This binding protects E2 from metabolic disposition. In ovariectomized rats, pancreatic E2 levels remain elevated for up to 96 h after a single E2 injection, consistent with PDIp acting as an intracellular E2 reservoir. Purification of endogenous PDIp from pancreatic tissue, radioligand binding assay, in vivo ovariectomized rat model with E2 tissue quantification The Biochemical journal Medium 22747530
2013 Computational homology modeling of the PDIA2 (PDIp) b-b' domain identified His278 as critical for estradiol binding via a hydrogen bond with the 3-hydroxyl group. This was experimentally confirmed by selective mutations of predicted binding-site residues and selective modifications of ligand functional groups. Homology modeling, docking, site-directed mutagenesis of binding-site residues, ligand functional group modification Current medicinal chemistry Medium 23931275
2018 PDIA2 (PDIp) physically interacts with multiple pancreatic digestive enzymes in vivo (identified by MS after acid quenching and thiol alkylation to stabilize transient disulfide-linked complexes). PDIp prevents aggregation of proelastase in cultured cells when co-expressed, and enhances secretion of properly folded proelastase that can be activated by trypsin, establishing digestive enzymes as physiological substrates. Acid quenching/thiol alkylation to trap complexes, MS identification of endogenous substrates from mouse pancreas, co-expression experiments in cultured cells The Journal of biological chemistry High 30315102
2022 PDIA2 translocates from the ER to mitochondria under AOM/DSS-induced ER stress conditions in colon cancer, where it interacts with components of mitochondrial complexes I and II to inhibit oxidative phosphorylation and increase glycolysis. Knockdown of PDIA2 in colon cancer cells restores the metabolic balance and suppresses xenograft tumor growth. Co-immunoprecipitation (PDIA2 with complex I/II components), subcellular fractionation/localization, metabolic assays (oxygen flux, extracellular acidification, targeted metabolomics), xenograft model with PDIA2 knockdown Frontiers in oncology Medium 35860571
2024 PDIA2 activates tissue factor (TF) on tumor-derived extracellular vesicles (EVs) through its isomerase activity, triggering a pro-thrombotic cascade. TF-containing EVs also activate Src kinase inside PCa cells to enhance androgen receptor (AR) signaling ligand-independently. Androgen deprivation suppresses clathrin-dependent endocytosis, enhancing PDIA2 translocation to the cell membrane and EVs. Co-recruitment of AR and FOXA1 to the PDIA2 promoter is required for PDIA2 transcription under androgen-deprived conditions. Blocking PDIA2 isomerase activity suppresses pro-coagulation activity and castrate-resistant tumor growth. In vitro and in vivo models, EV isolation and characterization, TF activity assay, isomerase inhibition experiments, Src kinase activation assay, chromatin immunoprecipitation (AR/FOXA1 at PDIA2 promoter), xenograft models Oncogene Medium 38589675

Source papers

Stage 0 corpus · 20 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2004 Identification of the protein disulfide isomerase family member PDIp in experimental Parkinson's disease and Lewy body pathology. Brain research 115 15353226
1996 Characterization and chromosomal localization of a new protein disulfide isomerase, PDIp, highly expressed in human pancreas. DNA and cell biology 64 8561901
1997 Molecular characterization of a pancreas-specific protein disulfide isomerase, PDIp. DNA and cell biology 44 9115635
2000 Specificity in substrate binding by protein folding catalysts: tyrosine and tryptophan residues are the recognition motifs for the binding of peptides to the pancreas-specific protein disulfide isomerase PDIp. Protein science : a publication of the Protein Society 43 10794419
2013 Clinicopathological features and CCT2 and PDIA2 expression in gallbladder squamous/adenosquamous carcinoma and gallbladder adenocarcinoma. World journal of surgical oncology 31 23782473
2001 The pancreas-specific protein disulphide-isomerase PDIp interacts with a hydroxyaryl group in ligands. The Biochemical journal 27 11237859
2010 Human pancreas-specific protein disulfide-isomerase (PDIp) can function as a chaperone independently of its enzymatic activity by forming stable complexes with denatured substrate proteins. The Biochemical journal 26 20423326
2009 Human pancreas-specific protein disulfide isomerase homolog (PDIp) is an intracellular estrogen-binding protein that modulates estrogen levels and actions in target cells. The Journal of steroid biochemistry and molecular biology 26 19429457
1997 Pancreas specific protein disulfide isomerase, PDIp, is in transient contact with secretory proteins during late stages of translocation. FEBS letters 25 9136904
2012 N-linked glycosylation modulates dimerization of protein disulfide isomerase family A member 2 (PDIA2). The FEBS journal 19 23167757
2022 PDIA2 Bridges Endoplasmic Reticulum Stress and Metabolic Reprogramming During Malignant Transformation of Chronic Colitis. Frontiers in oncology 14 35860571
2009 Human pancreas-specific protein disulfide isomerase homolog (PDIp) is redox-regulated through formation of an inter-subunit disulfide bond. Archives of biochemistry and biophysics 14 19150607
2018 Identification of the physiological substrates of PDIp, a pancreas-specific protein-disulfide isomerase family member. The Journal of biological chemistry 11 30315102
2024 PDIA2 has a dual function in promoting androgen deprivation therapy induced venous thrombosis events and castrate resistant prostate cancer progression. Oncogene 4 38589675
2020 Genetic Variants in Host Protein Disulfide Isomerase 2 (PDIA2) are Associated with Susceptibility to Chlamydia Trachomatis Infection. Journal of the Association of Genetic Technologists 3 33293489
2013 Usefulness of molecular modeling in characterizing the ligand-binding sites of proteins: experience with human PDI, PDIp and COX. Current medicinal chemistry 2 23931275
2012 PDIp is a major intracellular oestrogen-storage protein that modulates tissue levels of oestrogen in the pancreas. The Biochemical journal 2 22747530
2011 Both PDI and PDIp can attack the native disulfide bonds in thermally-unfolded RNase and form stable disulfide-linked complexes. Biochimica et biophysica acta 2 21238616
2023 The involvement of PDIA2 gene in the progression of renal cell carcinoma is potentially through regulation of JNK signaling pathway. Clinical & translational oncology : official publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico 1 37017923
2023 PDIA2 variant associated with vitiligo. Skin health and disease 0 37799362

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