Thioredoxin-related transmembrane protein 4 (TMX4)

Thioredoxin-related transmembrane protein 4 (TMX4) is a type I ER-resident transmembrane protein and the only reductase member of the TMX subfamily of the protein disulfide isomerase (PDI) family. Its N-terminal domain contains a catalytically active thioredoxin-like fold (with a CPSC redox motif) facing the ER lumen, enabling it to catalyze the reduction of disulfide bonds in substrate proteins, thus facilitating protein folding and quality control. Distinct from most PDI family members, TMX4 lacks a C-terminal ER-retention sequence but possesses a di-arginine motif for ER localization. TMX4 participates in protein folding through direct interaction with ER chaperones (calnexin and ERp57) and is involved in ER redox regulation. TMX4 is ubiquitously expressed, with high expression in melanoma, and has emerging functional roles in platelet biology and ER/nuclear envelope homeostasis. The gene is known as TXNDC13, PDIA14, and other aliases, and encodes a 349-amino acid protein. Summary: TMX4 is an ER-resident thioredoxin family enzyme crucial for disulfide reduction, redox regulation, and has genetic and functional disease associations, but no established drugs or clinical biomarkers yet.

Other names

TXNDC13KIAA1162PDIA14DJ971N18.2PSEC0095Thioredoxin domain-containing protein 13Protein disulfide isomerase family A, member 14

Not applicable as no interacting drugs are clearly documented. TMX4 itself functions enzymatically as a protein disulfide reductase, facilitating reduction of disulfide bonds in substrate proteins within the ER.