Alpha and beta thyroid hormone receptors bind immediately adjacent to the rat growth hormone gene TATA box in a negatively hormone-responsive promoter region.

Abstract

We report that alpha and beta type rat thyroid hormone receptors bind specifically and with high affinity to the 10-base pair sequence immediately 3' of the rat growth hormone TATA box (positions -25 to -16) in a region of the rat growth hormone promoter which can be negatively hormone responsive (nTRE). The receptors have approximately 7-fold lower affinity in vitro for the nTRE than for the thyroid hormone-responsive enhancer of the rat growth hormone gene (TRE). Proteins extracted with high salt concentration from rat pituitary cell nuclei enhance binding of the receptors to both the TRE and nTRE. A modification of the avidin-biotin complex DNA binding assay which enhances the sensitivity of the assay approximately 100-fold was used in these studies. The immediate proximity of a receptor binding site to the rat growth hormone TATA box suggests that direct interaction between receptor and TFIID (the TATA binding protein) mediates nTRE activity.