A method for structure determination of GPCRs in various states

Area of Science:

• Structural biology
• Biochemistry
• Molecular pharmacology

Background:

• G-protein-coupled receptors (GPCRs) are critical membrane proteins mediating cellular responses to external stimuli.
• Understanding GPCR functional states is essential for drug discovery and molecular biology.
• Current methods for GPCR structure determination often require complex preparations involving associated signaling proteins.

Purpose of the Study:

• To develop a universal and effective method for determining GPCR structures using cryo-electron microscopy (cryo-EM).
• To elucidate the structural basis of GPCR activation and ligand interactions without needing GPCR-signaling protein complexes.
• To provide new structural insights into the beta2-adrenergic receptor (β2AR) and the adhesion GPCR ADGRL3.

Main Methods:

• Development of a novel cryo-EM technique for GPCR structure determination.
• Application of the method to the β2AR with antagonistic and agonistic ligands.
• Structure determination of the adhesion GPCR ADGRL3 in its apo state.

Main Results:

• Successfully determined GPCR structures without requiring GPCR-signaling protein complexes.
• Captured distinct structural states of the β2AR, including an intermediate state stabilized by a partial agonist.
• Revealed the compact fold of inactive ADGRL3 and significant conformational changes necessary for adhesion GPCR activation.

Conclusions:

• The developed cryo-EM method offers a versatile approach for GPCR structure determination.
• The new structures provide critical insights into GPCR function, ligand binding, and activation mechanisms.
• This method is expected to accelerate GPCR research and facilitate the development of novel therapeutics targeting GPCRs.