TISSUE-SPECIFIC AND CELL-SPECIFIC DISTRIBUTION OF PROTEINS THAT INTERACT WITH THE HUMAN THYROID-HORMONE RECEPTOR-BETA

Variable tissue effects of thyroid hormones depend on many factors tha t could include tissue-specific proteins that interact with nuclear th yroid hormone receptors. To study this possibility, direct interaction s between the thyroid hormone receptor beta and other nuclear proteins were examined by far western blotting assays. Purified hTR beta bound to human retinoid X receptor alpha and human general transcription fa ctor IIB (TFIIB) immobilized on a membrane and it also bound to severa l different hTR beta binding proteins (TRBPs) in nuclear extracts from rat brain, kidney, liver, GH3 cells, and HeLa cells. Each tissue or c ell line showed unique distributions of TRBPs and some TRBPs were regu lated by thyroid hormone in vivo. These studies show that multiple pro teins interact with the hTR beta and they could be important in regula ting TR function.