[Cytoplasmic thyroxine-binding protein: the role of RNA in the interactions between thyroxine receptor and cell nuclei].

The presence of 3H-orotic acid in the cytoplasmic receptor fraction isolated in our laboratory, the sensitivity of this fraction to treatment with RNAases accompanied by a shift of the absorption peak of the receptor preparation towards the long-wave region as well as the use of the absorption filter technique point to the existence of ternary thyroxine-thyroxine-binding protein-RNA complex in the cytoplasm. It was found that the cytoplasmic hormone-receptor complex of thyroxine is a genetically active form which can interact with the nuclei and modify the activity of chromatin. The role of RNA in these interactions is discussed.