Structural organization of G-protein-coupled receptors

Area of Science:

• Structural Biology
• Biophysics
• Computational Chemistry

Background:

• G-protein-coupled receptors (GPCRs) are crucial membrane proteins involved in numerous physiological processes.
• Understanding the atomic-resolution structure of GPCRs is vital for drug discovery and understanding cellular signaling.
• Previous methods have limitations in resolving the detailed structures of these complex transmembrane proteins.

Purpose of the Study:

• To calculate atomic-resolution structures of the transmembrane 7-alpha-helical domains of 26 GPCRs and related proteins.
• To identify key structural features contributing to GPCR stability and function.
• To provide models that agree with experimental data and offer insights into GPCR-ligand interactions.

Main Methods:

• Utilized distance geometry calculations to model GPCR structures.
• Applied interhelical hydrogen bonds as distance constraints derived from known protein family structures.
• Incorporated previously established computational methods [Pogozheva et al., Biophys. J., 70 (1997) 1963].

Main Results:

• Developed atomic-resolution structural models for 26 GPCRs, including various receptor types and retinochrome/Duffy antigen.
• Identified stabilizing structural features: extensive interhelical H-bond networks, sulfur-aromatic clusters, close side-chain packing, disulfide bonds, and a Zn2+ binding site.
• Revealed functional and evolutionary insights: a conserved 'minicore' of 43 residues, correlated residue replacements, Na+ binding sites, and complementary ligand-binding pockets.

Conclusions:

• The calculated GPCR models accurately reflect structural stability and functional characteristics.
• These models provide a framework for understanding GPCR evolution and ligand binding.
• The findings are consistent with a wide range of experimental data, validating the computational approach.