Modeling GPCR active state conformations: the β(2)-adrenergic receptor

Area of Science:

• Structural Biology
• Computational Chemistry
• Pharmacology

Background:

• G protein-coupled receptors (GPCRs) are crucial drug targets, but modeling their active states remains challenging.
• Recent advances in GPCR structural biology and opsin crystal structures provide new insights for homology modeling.

Purpose of the Study:

• To generate a validated computational model of the active conformation of the β(2)-adrenergic receptor.
• To assess the model's accuracy in predicting ligand binding and G protein interactions.

Main Methods:

• Combined structural information from inactive and active GPCR states, including opsin.
• Employed molecular dynamics simulations incorporating experimental data (zinc binding, spin labeling, spectroscopy).
• Validated the model using manual docking, site-directed mutagenesis, and virtual screening.

Main Results:

• Developed a robust model of the active β(2)-adrenergic receptor, highlighting conformational changes in TM6, TM5, and TM7.
• Virtual screening accurately predicted selectivity for β-adrenergic agonists, stereoisomers, and receptor subtypes.
• The model successfully docked a stimulatory G protein C-terminal peptide, consistent with experimental data.

Conclusions:

• The generated active β(2)-adrenergic receptor model is extensively validated and agrees well with diverse experimental findings.
• The model provides a powerful tool for understanding GPCR activation mechanisms and guiding drug design.
• The employed methodology is transferable for modeling the active states of other GPCRs.