The resulting messenger RNA from gene activation can then be translated into the respective protein to produce a physiological response. However, this mechanism is not as simple as it appears. The hormone-receptor complex interacts with other nuclear players, such as transcription factors, adapter proteins, coactivators, and transacetylases. The 1997 Cell paper describes a novel cofactor, ACTR, which directly binds nuclear receptors and stimulates their transcriptional activities in a hormone-dependent fashion. He adds that the association of multiple HAT proteins had not been observed before this paper.
HATs are hot molecules because they are implicated in transcriptional activation.
HAT proteins acetylate specific lysines within histone proteins. Acetylation appears to decondense chromatin, which allows transcriptional machinery access to the DNA code. The Evans lab found evidence to support this theory in the follow-up to the 1997 Cell paper. They provided in vivo evidence that histone acetylation is essential to hormone-induced gene activation. Both steroid hormones and vitamins A and D induced hyperacetylation of histones at gene promoters.