Nanoluciferase-based complementation assay for systematic profiling of GPCR-GRK interactions.

Area of Science:

• Pharmacology and Molecular Biology
• G protein-coupled receptor (GPCR) signaling
• Enzyme kinetics and protein-protein interactions

Background:

• G protein-coupled receptor kinases (GRKs) are crucial enzymes regulating GPCR activity through phosphorylation.
• GRKs mediate GPCR desensitization and internalization by recruiting arrestins.
• A systematic method to profile GPCR-specific GRK preferences has been lacking.

Purpose of the Study:

• To establish a standardized assay for systematically determining GPCR preferences for all seven GRKs (GRK1-7).
• To characterize the GRK recruitment profiles and ligand-dependent kinetics for specific GPCRs, including the mu-opioid receptor (MOR).

Main Methods:

• Utilized a split Nanoluciferase (NanoBiT) complementation system to detect GRK-GPCR interactions.
• Applied the assay to a panel of GPCRs, including MOR, 5-HT_1A, B2AR, CXCR3, AVPR2, CGRPR, ACKR2, and ACKR3.
• Analyzed GRK recruitment profiles, kinetics, and ligand activity for MOR.

Main Results:

• The NanoBiT assay provided highly reproducible GRK recruitment profiles for tested GPCRs.
• Distinct GRK preferences were observed across different GPCRs, including arrestin-biased receptors.
• Detailed GRK fingerprint, kinetics, and ligand activity were elucidated for MOR.

Conclusions:

• The developed NanoBiT complementation assay is a valuable tool for systematic GRK-GPCR interaction profiling.
• This methodology enables detailed characterization of GPCR regulation by specific GRKs and ligand effects.
• Understanding GRK-GPCR interactions is critical for drug development, particularly for targets like MOR in pain management.