Biological Background

The Glucagon-Like Peptide-1 Receptor (GLP-1R) is a class B GPCR crucial for glucose homeostasis and incretin pathway regulation. Exendin-4, a potent GLP-1R agonist, serves as a gold standard research tool for diabetes and metabolic studies. With superior stability and DPP-4 resistance, exendin-4 enables comprehensive GLP-1R pharmacology characterization.

This bioassay kit supports pharmaceutical companies and researchers developing GLP-1 receptor agonist therapies for diabetes, obesity, and metabolic disorders. Applications include drug characterization, potency testing, neutralizing antibody screening, and stability studies.

Eurofins DiscoverX's PathHunter® Exendin-4 kit provides ready-to-use engineered CHO-K1 cells for sensitive β-arrestin recruitment detection, delivering reliable results for GLP-1R drug development applications.

Product Highlights
  • Functional β-arrestin recruitment assay using PathHunter® EFC technology for G-protein-independent GLP-1R signaling detection
  • Universal platform ideal for characterizing agonists, antagonists, and neutralizing antibodies with enhanced sensitivity to partial agonists
  • Complete kit includes cells, detection reagents, plating media, control agonist (exendin-4), and assay plates for immediate use
  • Gold standard exendin-4 reference compound with superior stability and DPP-4 resistance for reliable GLP-1R characterization

PathHunter CHO-K1 Exendin-4 Bioassay Assay Principle

PathHunter Exendin-4 Bioassay Assay Principle

β-Arrestin Recruitment and PathHunter® Technology A. GLP-1R ligand-induced β-arrestin-2 recruitment activates signaling cascades independently of G-protein signaling to provide a stoichiometric, non-amplified signal. Upon exendin-4 or other GLP-1R agonist binding, the activated GLP-1R is phosphorylated by GPCR kinases, leading to β-arrestin-2 recruitment. This β-arrestin-2 binding blocks G protein-mediated signaling and results in GLP-1R internalization (endocytosis) and signal desensitization. Subsequently, the GLP-1R is recycled back to the plasma membrane or degraded in the lysosome. This stoichiometric (1 receptor: 1 ligand), non-amplified system requires full ligand occupancy to generate maximum signal, which provides superior sensitivity for detecting GLP-1R antagonists and improved differentiation between partial and full agonists compared to amplified cAMP second messenger systems. By analyzing the GLP-1R β-arrestin pathway, researchers can fine-tune compound characterization when screening antagonists, distinguish between full, super, and partial agonists, and assess ligand bias by comparing β-arrestin recruitment versus G-protein signaling profiles.
B. PathHunter® Exendin-4 bioassays utilize EFC technology. GLP-1R is fused with the small enzyme donor fragment ProLink™ (PK) and co-expressed in CHO-K1 cells stably expressing β-arrestin-2 fused to the larger enzyme acceptor fragment (EA). GLP-1R activation by exendin-4 or test compounds stimulates β-arrestin-2 recruitment to the PK-tagged receptor, forcing complementation of the enzyme fragments and reconstituting active β-galactosidase enzyme. This interaction produces measurable enzyme activity detected using chemiluminescent PathHunter Detection Reagents. The β-arrestin recruitment assay offers an easy-to-use complement to cAMP and calcium G-protein–dependent pathways, enabling comprehensive GLP-1R compound pharmacology characterization—a universal platform that expands opportunities for developing novel GLP-1–based therapeutics.