Hormone Receptors Interact With Other Nuclear Proteins to Influence Hormone Responsiveness

Nuclear hormone receptors comprise some of the best-studied transcriptional systems in eukaryotic molecular biology. Steroids are small lipophilic molecules that cross the blood–brain barrier easily and are widely distributed in the brain. Experiments have been divided into two parts: determining the molecular biology of the nuclear hormone receptors themselves and investigating other nuclear proteins that go under the names coactivators and corepressors. The behavioral mechanisms best worked out are those that control the courtship and mating behaviors of female laboratory animals. A significant number of genes have the following two properties: they are turned on by estrogen administration and their products foster female reproductive behaviors. Nuclear hormone receptors do not sit by themselves on the DNA of neurons and glia, facilitating or repressing transcription. Instead, they participate in assemblies of substantial numbers of proteins that mediate their genomic effects. Such nuclear proteins either foster or block the formation of a complex bridge between the hormone-dependent enhancer sequence and the basal transcriptional machinery.