Dahlman-Wright K, Grandien K, Nilsson S, Gustafsson J A, Carlstedt-Duke J
Department of Medical Nutrition, Karolinska Institutet, Huddinge University Hospital, Sweden.
J Steroid Biochem Mol Biol. 1993 Apr;45(4):239-50. doi: 10.1016/0960-0760(93)90338-w.
The glucocorticoid and thyroid hormone receptors have the capacity to bind as dimers to palindromic DNA-binding sites. Protein-protein interactions between the DNA-binding domains of glucocorticoid receptor dimers restrict the DNA-binding to elements where the half-sites are separated by three base pairs, whereas DNA-binding by the thyroid hormone receptor does not appear to require a strict half-site spacing. We have previously shown that a five amino-acid segment close the the C-terminal zinc-binding site (D-box) was involved in dimerization of the glucocorticoid receptor (GR) DNA-binding domain (Dahlman-Wright et al., 1991, J. Biol. Chem., 266, 3107-3112). Here we provide functional evidence, using mutated thyroid hormone receptor DNA-binding domains, that this five amino acid segment (D-box) of the GR interacts with the equivalent segment on the second DNA-binding domain in the dimer. In contrast, the thyroid hormone receptor DNA-binding domain binds to palindromic thyroid hormone response elements in a weakly co-operative manner, independent of the D-box.
