[Molecular basis for the action of thyroid hormones].

The mode of action of thyorid hormones at molecular level is described. The hormone reaches the target cell presumably by active transport and then it binds specifically to the plasma membrane, cytosol and mitochondria. Yet from the standpoint of its action, the most important binding is that to the cell nucleus. The nucleus receptor was partially isolated and its physico-chemical properties were determined. The hormone-receptor complex induces gene expression involving generation of specific ribonucleic acids and subsequent production of specific proteins (enzymes). The latent time interval for protein production is of varying length. Triiodothyronine induces in the liver the production of a specific protein which plays a role in the synthesis, metabolism, and storage of lipids.