Thioredoxin domain-containing protein 15(TXNDC15) is a single-pass type I membrane protein. Mature Human TXNDC15 consists of a 289 amino acid (aa) extracellular region (ECD) with one thioredoxin domain, a 21 aa transmembrane domain, and a 18 aa cytoplasmic region. It has 2 isoforms produced by alternative splicing. Thioredoxins comprise a family of small proteins that, by catalyzing the oxidation of disulfide bonds, participate in redox reactions throughout the cell. Proteins that contain thioredoxin domains do not necessarily convey the oxidative properties of thioredoxins, but generally function as disulfide isomerases that enzymatically rearrange disulfide bonds found in various proteins.