Increased Cholesterol Interactions in the Active Conformational State of the Glucagon-Like Peptide-1 Receptor.

The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor (GPCR) that plays an important role in metabolic regulation, and consequently is a target for type 2 diabetes and obesity therapeutics. Although cholesterol has been reported to be implicated in receptor activation, its interactions with the receptor during the activation cycle have not been probed. Using coarse-grained molecular dynamics simulations, we have characterized the cholesterol interactions with GLP-1R in four conformational states: the inactive, partially active, GLP-1-bound active, and exenatide-bound active conformational states. We observed that the cholesterol hotspots vary between the receptor states with an increased enrichment of cholesterol around the receptor in the active conformational states. Importantly, more favorable interaction energetics and increased residence times of cholesterol were identified in the active conformational state of the receptor, although lower in magnitude than previously reported. Notably, subtle differences could be distinguished between the GLP-1- bound and exenatide-bound receptor, underlining the ligand specific effects. Our findings emphasize the increased selectivity of cholesterol towards the active state of GLP-1R and highlight the role of conformational dynamics in receptor-lipid interplay. Our work helps to understand how cholesterol modulates GLP-1R, with potential effects on its role as a regulator in lipid metabolism, thereby opening avenues to leverage these lipid interactions in targeted drug therapy.