Activation by steroid hormone binding

Transcriptional enhancers are regulatory regions
of DNA that increase the rate of transcription.
Their spacing and orientation vary relative
to the starting point of transcription. An enhancer
is activated by binding to a hormone–receptor
complex. This activates the promoter,
and transcription begins (active gene). Numerous
important genes in mammalian development
are regulated by steroids (steroid-responsive
transcription). The latter include glucocorticoids
and mineralocorticoids, the steroids of
glycogen and mineral metabolism; sex hormones,
which function in embryonic sex differentiation
and control of reproduction; and
others. Normal bone development and function
are under the control of steroidlike vitamin D.
Another steroidlike hormone is retinoic acid, an
important regulator of differentiation during
embryogenesis (morphogen). These hormones
initiate their physiological effects by association
with corresponding steroid-specific transcellular
receptors (hormone–receptor complex).