Transthyretine - a Thyroxine Binding Protein
The thyroid hormones tetraiodothyronine (thyroxine or T4) and triiodothyronine (T3) are essential for a number of metabolic processes. Molecules whose spatial structures allow weak interactions with the polar hormones are generally used as receptors.
Thyroid Hormones |
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Tetraiodothyronine (Thyroxine) |
Triiodothyronine |
The tetrameric transthyretine can be considered a thyroxine binding protein. It is found in human blood plasma where it carries out a considerable part of the thyroxine transport. Some 80 % of thyroxine is transported to the brain bound to transthyretine.
There are two binding sites for thyroxine in each tetrameric unit.
Transthyretine also has acceptor sites for retinol (vitamine A).