ERp90/TXNDC16 is a soluble ER-luminal glycoprotein with about five potential thioredoxin domains, none of which contain a canonical CXXC active-site motif; it directly interacts with the ERAD flavoprotein ERFAD (FOXRED2), suggesting a role in substrate recruitment/delivery to the ERAD retrotranslocation machinery.

TXNDC16 is an ER-luminal glycoprotein that is secreted from human cell lines because its KDEL ER-retrieval motif is masked and non-functional; it is a meningioma-associated antigen, and a previously reported exosomal secretion could not be confirmed.

Authoritative review that classifies ERp90/TXNDC16 as a non-catalytic PDI-family member whose thioredoxin-like domains carry non-canonical motifs (CX8C, CX9C, CX6C) rather than active CXXC, and places it within the ERAD retrotranslocation network alongside factors such as OS-9 and SEL1L.

Review of meningioma liquid-biopsy approaches that summarizes prior work on TXNDC16 as a meningioma-associated antigen, noting a five-epitope autoantibody panel discriminating meningioma from healthy sera with ~90% sensitivity and ~83.7% specificity as a proof-of-concept serology biomarker.

Large PDI-family ER-luminal glycoprotein (ERp90) with a thioredoxin domain and a masked, non-functional KDEL ER-retention motif; interacts with FOXRED2 (ERFAD); secreted.