Sex steroid hormones (e.g. estrogens and androgens) are synthesized from cholesterol in a complex set of reactions and that the intracellular action of these hormones is transmitted through their cognate steroid hormone receptor (e.g. estrogen receptor and androgen receptor, respectively). These receptors contain domains involved in ligand binding, DNA binding and transcriptional activation (AF-1 and AF-2). The transcriptional effects of the steroid hormone receptors are elicited through the recruitment and actions of steroid hormone receptor coactivators and corepressors. It is the actions and interactions of the coregulators that determine the transcriptional outcome of the gene promoter. Steroid responsive genes can be classified as either "primary" or "secondary", depending on the requirement for de novo protein synthesis and the rapidity of the response.