Related Experiment Video
Updated: Aug 15, 2026

Quantifying Agonist Activity at G Protein-coupled Receptors
Published on: December 26, 2011
Historical review: Negative efficacy and the constitutive activity of G-protein-coupled receptors
Tommaso Costa1, Susanna Cotecchia
1Department of Pharmacology, Istituto Superiore di Sanità, Italy. tomcosta@iss.it
Abstract:
The idea that a receptor can produce signalling without agonist intervention and that several antagonists can be 'active' in repressing such spontaneous activity is contained in the concept of ligand-induced conformational changes. Yet, this idea was neglected by pharmacologists for many years. In this article, we review the events that brought inverse agonism and constitutive activity to general attention and made this phenomenon a topic of current research. We also suggest a classification of antagonists based on the cooperativity that links their primary site of interaction with other functional domains of the receptor.
Related Concept Videos
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
G Protein-coupled Receptors
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
Activation and Inactivation of G Proteins
The Two-State Receptor Model
The binding affinity of a drug determines its interaction with one...
Transducer Mechanism: G Protein–Coupled Receptors
GPCRs are also called heptahelical, 7TM, or...
G-protein Coupled Receptors

