When a protein or peptide hormone binds to its receptor, a hormone-receptor complex is formed.
This hormone-receptor complex then binds to DNA, causing activation or repression of gene expression and, ultimately, a specific biological response.
Cofactors mediate the stabilization of hormone-receptor complex
and they regulate functional activities.
The binding of a hormone to its receptor can be understood as a chemical reaction that is governed by the law of mass action, where the hormone (H) and receptor (R) are the reactants and the hormone-receptor complex (HR) is the product:
D] is the equilibrium dissociation constant (a measure of affinity) and [H], [R], and [HR] are concentrations of hormone, receptor, and the hormone-receptor complex, respectively.
In the nucleus, the hormone-receptor complex
when bound to DNA stimulates or represses the expression of certain genes, thereby affecting protein synthesis.
2] or estrogenic mimics bind to ERs, receptor dimerization and recruitment of transcriptional comodulators are initiated, and the hormone-receptor complex
binds to the estrogen response element (ERE) and subsequently regulates transcription in an ordered and cyclic manner (Metivier et al.
Once combined, the hormone-receptor complex
stimulates processes such as ovulation, sperm production, the emergence of adult sexual characteristics, and changes in blood chemistry.
Each hormone has a "high affinity" for its particular receptor, and upon binding together like a "lock and key", the hormone-receptor complex
signals genetic expression in the cell nucleus, whether it be to "turn on" or "turn off" biological activity.