Thioredoxin Like Protein 1 (TXNL1)

The predicted 289-amino acid, 32.3-kD protein has 2 distinct domains: an N-terminal domain, which is 43% identical to human TXN, and a C-terminal domain, which showed no homology to other proteins in the sequence databases. The active site sequence, located within the N-terminal domain, is that of a thioredoxin-like protein; compared to the active site sequence of TXN, it has a single amino acid substitution. Unlike other thioredoxin-like proteins, TXL did not act as a substrate for thioredoxin reductase in an insulin assay. Since TXL has an additional 184 amino acids at its C terminus relative to other mammalian thioredoxins, the authors tested a TXL protein that lacked the C-terminal domain and found that this truncated form was also unable to act as a substrate in an insulin assay.