Hormone receptor

A hormone receptor is a receptor protein on the surface of a cell or in its interior that binds to a specific hormone. The hormone causes many changes to take place in the cell.

Binding of hormones to hormone receptors often trigger the start of a biophysical signal that can lead to further signal transduction pathways, or trigger the activation or inhibition of genes. [ [http://www.bio-balance.com/Graphics.htm http://www.bio-balance.com/ ] ]

Types of Hormone Receptors

* Peptide hormone receptors are often transmembrane proteins. They are also called G-protein-coupled receptors, sensory receptors or ionotropic receptors. These receptors generally function via intracellular second messengers, including cyclic AMP (cAMP), inositol 1,4,5-trisphosphate (IP3) and the calcium (Ca²⁺)-calmodulin system.

* Steroid hormone receptors and related receptors are generally soluble proteins that function through gene activation. Their response elements are DNA sequences (promoters) that are bound by the complex of the steroid bound to its receptor. The receptors themselves are zinc-finger proteins. [ [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/SteroidREs.html Steroid Hormone Receptors and their Response Elements] ] These receptors include those for glucocorticoids, estrogens, androgens, thyroid hormone (T3), calcitriol (the active form of vitamin D), and the retinoids (vitamin A).

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