Structural insights into the activation of G protein-coupled receptor 119 by the agonist GSK1292263 and ligands selectivity among novel cannabinoid receptors.

GPR119, a class A G protein-coupled receptor (GPCR), belongs to the novel cannabinoid receptor subfamily along with GPR55 and GPR18. It plays a crucial role in insulin secretion and glucose homeostasis, representing a promising therapeutic target for type 2 diabetes. Here, we report the cryo-EM structure of the human GPR119-GSK1292263-G complex at 3.02 Å resolution, revealing the ligand-binding mode characterized by extensive aromatic and hydrophobic interactions. Structure-based mutagenesis and cAMP assays confirmed the essential roles of residues F157, W265, F241, and W238. Compared with AR231453, GSK1292263 lacks halogen-π and other stabilizing interactions, potentially contributing to its relatively lower binding stability. Molecular docking of GSK1292263 analogs further clarified the pharmacophore requirements for potency enhancement. Molecular dynamics simulations supported the conformational stability of the GPR119-ligand complex and reinforced the observations from the static structure. Within the novel cannabinoid receptor subfamily, the structural convergence and subtype selectivity of GPR119 agonists may arise from its deeper and more aromatic binding pocket, whereas GPR55 primarily relies on a polar extracellular cavity for flexible ligand recognition. The homology-modeled structure of GPR18 suggests a compact binding pocket favoring bent or smaller ligands. Collectively, our findings provide a structural framework and mechanistic insights for the rational design of selective GPR119-targeted therapeutics for metabolic disorders.