Anterior gradient protein 3 (AGR3)

Anterior gradient protein 3 (AGR3) is a small, single-domain member of the protein disulfide isomerase (PDI) family, encoded by the AGR3 gene in humans[1][4][6]. Unlike most PDI family enzymes, AGR3 lacks the canonical active-site motif required for thiol–disulfide exchange, suggesting limited or atypical isomerase activity[1]. AGR3 contains a thioredoxin fold and is localized to the endoplasmic reticulum, possessing a non-standard QSEL C-terminal motifs for ER retention[1]. It is predominantly expressed in ciliated airway epithelial cells, the oviduct, and some other tissues such as stomach, prostate, and liver[1][6]. AGR3 is required for calcium-mediated regulation of ciliary beat frequency and mucociliary clearance in the airway[6], and is upregulated by androgens and estrogens. Its expression has been associated with hormone-responsive cancers, including breast and prostate cancer, and it has been suggested as both a potential therapeutic target and molecular marker in such contexts[1]. It may interact with mucins and participate in protein folding, though it is not induced by the unfolded protein response like many other PDIs[1]. Currently, no known drugs or direct inhibitors/modulators are described in the literature provided.

Other names

AG3PDIA18BCMP11hAG-3HAG3anterior gradient protein 3 homologbreast cancer membrane protein 11protein disulfide isomerase family A member 18UNQ642/PRO1272