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

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).

 

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