Thioredoxin

Thioredoxin (TXN) is a small redox-active protein that catalyzes dithiol-disulfide exchange reactions through reversible oxidation of its active site cysteine residues (UniProt: P10599). Beyond its core redox function, it participates in S-nitrosylation of target proteins including caspase-3, thereby modulating apoptotic signaling and cellular responses to nitric oxide. The protein also influences transcriptional activity through effects on AP-1 DNA-binding.

Thioredoxin is ubiquitously expressed and functions in multiple cellular compartments, contributing to antioxidant defense and redox-dependent signaling pathways. The UniProt record lists no primary disease associations, though its redox regulatory roles implicate it broadly in cellular stress responses.

In Alzheimer's disease, thioredoxin is significantly down-regulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics), with a mean log2 fold-change of −0.70. This reduction may reflect impaired antioxidant capacity and redox regulation in the AD brain, potentially contributing to oxidative stress and neurodegeneration characteristic of the disease.