Atomic force microscopy-single-molecule force spectroscopy unveils GPCR cell surface architecture

Area of Science:

• Cell biology
• Biophysics
• Pharmacology

Background:

• G protein-coupled receptors (GPCRs) are crucial cell surface proteins with largely unknown architecture.
• Understanding GPCRs' surface organization is key to their pharmacology.

Purpose of the Study:

• To investigate the architecture and spatial organization of GPCRs on living mammalian cell surfaces.
• To explore how receptor oligomeric states and activity influence their surface distribution.

Main Methods:

• Utilized atomic force microscopy-based single molecule force spectroscopy (AFM-SMFS) to probe individual GPCRs.
• Analyzed GPCR unfolding distances to determine oligomeric states and spatial arrangements.

Main Results:

• Identified distinct GPCR populations with varying oligomeric states, dependent on receptor type and expression levels.
• Demonstrated that oligomer size dictates spatial organization, forming nanoclusters or widespread distribution.
• Showed that receptor activity alters both oligomeric populations and spatial arrangement.

Conclusions:

• GPCRs exhibit complex, heterogeneous architectures at the cell surface, challenging previous single-population models.
• Oligomeric state and spatial organization are dynamic and activity-dependent, adding complexity to GPCR pharmacology.