Related Experiment Video
Updated: May 29, 2025

A Kinetic Fluorescence-based Ca2+ Mobilization Assay to Identify G Protein-coupled Receptor Agonists, Antagonists, and Allosteric Modulators
Published on: February 20, 2018
Molecular simulations reveal intricate coupling between agonist-bound β-adrenergic receptors and G protein
Yanxiao Han1, John R D Dawson1,2, Kevin R DeMarco1
1Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA.
Abstract:
G protein-coupled receptors (GPCRs) and G proteins transmit signals from hormones and neurotransmitters across cell membranes, initiating downstream signaling and modulating cellular behavior. Using advanced computer modeling and simulation, we identified atomistic-level structural, dynamic, and energetic mechanisms of norepinephrine (NE) and stimulatory G protein (Gs) interactions with β-adrenergic receptors (βARs), crucial GPCRs for heart function regulation and major drug targets. Our analysis revealed distinct binding behaviors of NE within β1AR and β2AR despite identical orthosteric binding pockets. β2AR had an additional binding site, explaining variations in NE binding affinities. Simulations showed significant differences in NE dissociation pathways and receptor interactions with the Gs. β1AR binds Gs more strongly, while β2AR induces greater conformational changes in the α subunit of Gs. Furthermore, GTP and GDP binding to Gs may disrupt coupling between NE and βAR, as well as between βAR and Gs. These findings may aid in designing precise βAR-targeted drugs.
Related Concept Videos
G-protein Coupled Receptors
Activation and Inactivation of G Proteins
GPCRs Regulate Adenylyl Cylase Activity
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...
Transducer Mechanism: G Protein–Coupled Receptors
GPCRs are also called heptahelical,...
The Two-State Receptor Model
The binding affinity of a drug determines its interaction with...

