3,5-Diiodothyronine
3,5-Diiodothyronine is an active thyroid hormone within the class of iodothyronines. It has two iodine atoms at positions 3 and 5 of its inner ring.Biological effects
3,5-T2 is an active thyroid hormone. It stimulates the TR-beta receptor for thyroid hormones and thus increases energy expenditure. It has agonistic effects at myocardial tissue and pituitary, which results in 3,5-T2 suppressing TSH release. 3,5-T2 is an allosteric regulator of the cytochrome c oxidase, the complex IV of the electron transport chain. It increases its activity by preventing the interaction of adenosine triphosphate as an allosteric inhibitor.Clinical significance
In nonthyroidal illness syndrome 3,5-T2 concentrations are increased. This could explain why patients with low T3 syndrome don't benefit from substitution therapy with thyroid hormones.
