Thioredoxin is a small protein that plays a crucial role in maintaining the balance of redox reactions within cells. It helps to regulate the oxidation and reduction processes, which are essential for various cellular functions, including metabolism and the response to stress. Thioredoxin contains a reactive site that can donate electrons, allowing it to reduce other proteins and maintain their proper function. This protein is found in many organisms, from bacteria to humans, and is involved in several important biological processes. Thioredoxin is also linked to the regulation of the immune system and has been studied for its potential role in cancer and other diseases, making it a significant focus in biomedical research.