What would happen if a hormone receptor did not bind to the right site?

Answer 1

I'm assuming you're asking what would happen if a receptor did not bind the proper hormone. The answer is a complex one because binding to a receptor does not necessarily mean that the receptor will be activated. Sometimes binding causes receptor inhibition; other times it can mean that the properties of the receptor change so that other hormones have an easier/harder time binding and activating it. But for the sake of giving an answer, let's say that we want to know what happens if a hormone binds and activates the wrong receptor. That answer is a relatively simple one: in most cases, the same events would take place that normally happen when the correct hormone binds the receptor.

Let's take an example of a relatively uncommon cause of hypertension called hypertension exacerbated in pregnancy. In this condition, there's a mutation in the receptor for the hormone aldosterone that allows other hormones besides aldosterone (eg, progesterone) to bind it and activate it. When progesterone levels are high, as in pregnancy, the extra progesterone binds and heavily activates the aldosterone receptor, and the receptor essentially "thinks" that aldosterone has bound. So the action of progesterone at the aldosterone receptor are the same as aldosterone itself; since aldosterone is a major contributor to blood pressure, blood pressure increases to very high levels.