Which term describes a compound that, upon receptor binding, stabilizes a receptor that is already producing a signal and reduces its activity?

Which term describes a compound that, upon receptor binding, stabilizes a receptor that is already producing a signal and reduces its activity?

• A. Agonist
• B. Inverse agonist
• C. Partial agonist
• D. Biased agonist

Answer: (B)

The concept being tested is constitutive receptor activity and inverse agonism. Some receptors signal at baseline even without a ligand. A compound that binds and shifts the receptor toward the inactive state, lowering this basal signaling, is an inverse agonist. It has negative efficacy, actively reducing activity below the baseline. An agonist would increase signaling by stabilizing the active form, a partial agonist would increase signaling but only to a submaximal level, and a biased agonist would preferentially trigger certain signaling pathways while still activating the receptor overall.

The concept being tested is constitutive receptor activity and inverse agonism. Some receptors signal at baseline even without a ligand. A compound that binds and shifts the receptor toward the inactive state, lowering this basal signaling, is an inverse agonist. It has negative efficacy, actively reducing activity below the baseline. An agonist would increase signaling by stabilizing the active form, a partial agonist would increase signaling but only to a submaximal level, and a biased agonist would preferentially trigger certain signaling pathways while still activating the receptor overall.