Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

Many hormones released by endocrine organs travel down in the blood and bind to specific receptors on the target cells. What then breaks that binding of the molecule with the receptor ? ( thus inactivating further stimulation of the target cell )

share|improve this question
up vote 1 down vote accepted

The binding is reversible typically; part of the potency of a drug is ow well and for how long it binds to its target. There's a natural equilibrium of binding and dissociation. Many drugs, once bound to their cognate receptor, cause a down regulation of their cognate receptor on the target cell. The bound/activated downstream signalling pathways may be inhibited by ubiquitination of the downstream signals themselves or upregulation of antagonists etc. The hormone itself has a half life, which is very important, thus levels naturally decrease and for some hormones this is incredibly rapid. Levels may decrease due to breakdown or excretion. Increase of binding hormones may decrease free hormone thus it's effect also.

share|improve this answer
Nice answer ! What is down regulation ? – biogirl Jul 28 '13 at 14:38
The number of receptors on cells are regulated by sometimes thousands of things. Often the hormone that activates a receptor in addition to its normal effects, also causes the numbers of its own receptors to go down. This is down regulation which prevents against too much of a hormone over a long period of time. – AndroidPenguin Jul 28 '13 at 15:56
Another point: even if a receptor is not downregulated or inactivated, certain signaling and gene regulatory circuits can prevent prolonged response. – WYSIWYG Jul 29 '13 at 3:31

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.