Class B GPCRs are divided into two subfamilies: B1 secretin receptors and B2 adhesion receptors. Members of the secretin receptor subfamily have large extracellular domains and bind to vasoactive intestinal peptide (VIP), pituitary adenylate cyclase-activating peptide (PACAP), corticotropin-releasing factor (CRF), parathyroid hormone (PTH), growth hormone-releasing hormone (GHRH), calcitonin gene-related peptide (CGRP), glucagon, and glucagon-like peptide (GLP). The adhesion receptor subfamily has nine subclasses and possesses unique N-terminal motifs, such as epidermal growth factor, cadherin, and immunoglobulin domains.
Figure 1. Dose-response curves of multiple agonists in Rat CTR&RAMP3 CRE-Luc CHO-K1 (C14) stable cell line
Left panel: CRE-luciferase reporter assay, measuring RLU signal upon agonist stimulation. Right panel: HTRF cAMP assay detecting intracellular cAMP levels. Both assays show distinct agonist potency ranking, confirming functional receptor activity, suitable for agonist screening and pharmacological profiling.
Figure 2. Dose-response curves of GIP in Rat GIPR CRE-Luc HEK293 (C2) stable cell line
Left panel: CRE-luciferase reporter assay, EC50 = 0.0043 nM. Right panel: HTRF cAMP assay, EC50 = 0.0018 nM. The consistent potent agonist response confirms functional Rat GIPR receptor, supporting pharmacological characterization and compound screening.
