TXNDC15 (thioredoxin domain-containing protein 15) is a single-pass type I transmembrane protein that contains a thioredoxin domain and is primarily localized in the cytoplasm. It plays a positive regulatory role in the Hedgehog signaling pathway within cilia and actively participates in the process of ciliogenesis, exerting significant influence on the structure and function of cilia-an essential cellular organelle. Additionally, TXNDC15 has been found to form mixed disulfide complexes with endoplasmic reticulum-resident protein disulfide isomerase (PDI) family members, such as ERp57, PDI, and ERp44, suggesting its involvement in protein folding and quality control processes. Notably, mutations in the TXNDC15 gene are associated with a rare and lethal genetic disorder known as Meckel-Gruber syndrome, which is caused by defects in ciliogenesis.