| Aspect | Finding | Best supporting citations |
|---|---|---|
| Identity/synonyms | **TXNDC16** is the human gene matching **UniProt Q9P2K2**; reported synonyms include **ERp90** and **KIAA1344**. Harz 2014 identifies TXNDC16 as a meningioma-associated antigen and notes it had previously been characterized as an **ER-luminal glycoprotein**. Harz 2014, *J Immunol*, published Sep 2014, URL: https://doi.org/10.4049/jimmunol.1303098 | (pqac-00000001, pqac-00000009) |
| Domains/motifs | TXNDC16/ERp90 is a **thioredoxin domain-containing, PDI-family-like** protein. Review evidence places it in the ER oxidoreductase network but notes its Trx-like motifs are **non-canonical/inactive** rather than classical catalytic CXXC motifs: **Trxl1-CX8C, Trxl2-CX9C, Trxl3-CX6C, Trxl4/5 inactive**. It also has a **predicted N-terminal 27 aa signal peptide** and a **C-terminal DKEL** KDEL-like motif. Patel 2020, *Cells*, Sep 2020, URL: https://doi.org/10.3390/cells9092138 | (pqac-00000003, pqac-00000008, pqac-00000002, pqac-00000016) |
| Subcellular localization | Experimental data support predominant **ER luminal/ER-associated localization**. TXNDC16-HA **colocalizes with PDI** by confocal microscopy, and deleting the signal peptide shifts localization from ER-associated to **cytosolic**, showing signal-peptide-dependent ER targeting. Harz 2014, *J Immunol*, Sep 2014, URL: https://doi.org/10.4049/jimmunol.1303098 | (pqac-00000000, pqac-00000010, pqac-00000016) |
| Secretion/extracellular presence | Despite ER-targeting features, TXNDC16 is also reported in **cell-culture supernatants** and **serum/circulating immune complexes**. Harz 2014 concluded secretion likely reflects a **masked/nonfunctional ER retrieval motif**; the authors could not confirm prior **exosomal** secretion in HEK293 cells. Korte 2024 highlights this as a basis for liquid-biopsy interest. Korte 2024, *Int J Mol Sci*, Apr 2024, URL: https://doi.org/10.3390/ijms25084195 | (pqac-00000001, pqac-00000004, pqac-00000005, pqac-00000014, pqac-00000015) |
| Proposed molecular function | Current evidence supports TXNDC16 as an **ER quality-control/thioredoxin-like scaffold or chaperone-associated factor**, not a well-established classical oxidoreductase enzyme. Because its Trx-like domains lack canonical catalytic motifs, the strongest inference is a role in **ER protein folding/quality control and ERAD-associated processes**, rather than a defined substrate-specific disulfide isomerase reaction. Patel 2020, *Cells*, Sep 2020, URL: https://doi.org/10.3390/cells9092138 | (pqac-00000003, pqac-00000008, pqac-00000006) |
| Interactions/complexes | TXNDC16/ERp90 is specifically linked to **ERAD retrotranslocation machinery**, with reported interactions involving **OS-9** and **SEL1L** in review summaries of ER glycoprotein quality control. This places TXNDC16 in pathways handling **misfolded glycoproteins** in the ER. Patel 2020, *Cells*, Sep 2020, URL: https://doi.org/10.3390/cells9092138 | (pqac-00000003, pqac-00000008) |
| Disease/biomarker evidence | The clearest disease-relevant evidence is in **meningioma serology**. TXNDC16 was identified as a **meningioma-associated antigen** with autoantibody reactivity; Korte 2024 reviews it as a **proof-of-concept liquid biopsy biomarker** based on serum autoantibodies/peptide arrays. Open Targets currently lists only **very weak association scores with zero underlying evidence rows** for diseases including meningioma, Alzheimer disease, chronic kidney disease, eye disease, and tinnitus, so these database associations should be treated cautiously. Open Targets query context available in this session. | (pqac-00000014, pqac-00000015, pqac-00000007) |
| Key statistics | Harz 2014 reports TXNDC16 has a **~93 kDa** predicted molecular mass and that a **5-epitope panel** derived from **163 overlapping peptides** discriminated meningioma vs controls with **87.2% accuracy**, **90% sensitivity**, and **83.7% specificity**; using all peptides performed much worse (**53.8% accuracy**, **24.2% specificity**, **77.3% sensitivity**). Korte 2024 reiterates the approximate **90% sensitivity / 83.7% specificity** result as support for non-invasive biomarker development. Harz 2014, *J Immunol*, Sep 2014, URL: https://doi.org/10.4049/jimmunol.1303098; Korte 2024, *Int J Mol Sci*, Apr 2024, URL: https://doi.org/10.3390/ijms25084195 | (pqac-00000009, pqac-00000014, pqac-00000015) |


*Table: This table summarizes the strongest available functional annotation evidence for human TXNDC16/ERp90, including identity verification, ER localization, inferred molecular role, ERAD associations, and current biomarker evidence. It is useful for distinguishing well-supported findings from weaker database-level disease associations.*