Question

If you only need to have a small amount of a ligand available to have it bind to a receptor and activate it, we would say that ligand has a _________ for that receptor. For example, when glucocorticoid levels are low, they bind to mineralocorticoid receptors (MR) first because they have a ___________ for glucocorticoids, whereas it takes a higher concentration of glucocorticoids to have them bind to glucocorticoid receptors (GR). GRs are g-protein coupled receptors, and we know that signaling cascades that result from neurotransmitters binding to metabotropic receptors tend to be more ______ than the changes in membrane polarization that result from neurotransmitters binding to ionotropic receptors.

Group of answer choices

High efficacy; higher efficacy; fast-acting

High affinity; higher affinity; long-lasting

Low efficacy; lower efficacy; long-lasting

Low affinity; lower affinity; fast-acting

Answer 1

Affinity describes strength of drug binding with receptor (“fit the lock”). Efficacy describes ability of drug-bound receptor to produce a response (“turn the key”). And thus higher efficacy means that even a low level of ligand binding will produce the effect and activate it.

Also, a fast-acting drug has an effect very quickly and thus rapid chnages occur a smentioned in the statement.

If you only need to have a small amount of a ligand available to have it bind to a receptor and activate it, we would say that ligand has a __high efficacy_______ for that receptor. For example, when glucocorticoid levels are low, they bind to mineralocorticoid receptors (MR) first because they have a ____high efficacy_______ for glucocorticoids, whereas it takes a higher concentration of glucocorticoids to have them bind to glucocorticoid receptors (GR). GRs are g-protein coupled receptors, and we know that signaling cascades that result from neurotransmitters binding to metabotropic receptors tend to be more __fast acting____ than the changes in membrane polarization that result from neurotransmitters binding to ionotropic receptors.

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