Thyroid hormones
The thyroid hormones function via a well-studied set of nuclear receptors, termed the thyroid hormone receptors. These receptors, together with corepressor molecules, bind DNA regions called thyroid hormone response elements (TREs) near genes. This receptor-corepressor-DNA complex can block gene transcription. Triiodothyronine (T3), which is the active form of thyroxine(T4), goes on to bind to receptors. The deiodinase catalyzed reaction removes an iodine atom from the 5' position of the outer aromatic ring of Thyroxine's (T4) structure. When triiodothyronine (T3) binds a receptor, it induces a conformational change in the receptor, displacing the corepressor from the complex. This leads to recruitment of coactivator proteins and RNA polymerase, activating transcription of the gene.
Kenneth Sterling
Sterling was one of the first researchers to use radioactive iodine to treat thyroid diseases. He used radioisotopic labels to study the metabolism of human serum proteins and red blood cells. He discovered that the body converts the pro-hormone thyroxine into triiodothyronine, the primary active form of thyroid hormone. This breakthrough led to a new field of thyroid hormone research and led to the first early studies on the mechanism of action of thyroid hormones. Sterling developed the equilibrium dialysis method for measuring free thyroxine, which remains the gold standard for evaluating free hormone levels in blood today. Sterling was a pioneering investigator identifying mitochondrial thyroid hormone receptors, shortened isoforms of the full-length, nuclear receptors. He wrote a chapter on thyroid hormone receptors in the fifth edition of "Werner's The Thyroid: A Fundamental and Clinical Text", which is known as "the bible of modern thyroidology."