Cholesterol Binds G Protein‐coupled Receptors in Conserved Sites Without Recurring Motifs

Abstract

Human G protein-coupled receptors (GPCRs) are an 800-member transmembrane receptor superfamily with huge pharmacological utility. Resolution breakthroughs in cryoelectron microscopy (cryo-EM) and continued evolution of x-ray crystallography have led to many GPCR structures with resolved bound lipids, especially the known GPCR stabilizer cholesterol. Cholesterol-GPCR binding is a well-studied allosteric regulator shared by many receptors and conserved binding sites could be a valuable pharmacological target. We examined the importance of specific sequence motifs, attempted to calculate a consensus motif, and compared the total evidence from both cryo-EM and x-ray structures. We analyze the current scope of cholesterol-GPCR binding interactions in Protein Data Bank structures, and find that 92% of cholesterol associates with GPCRs in 12 distinct sites on the transmembrane bundle, surprisingly without consensus binding residues. Additionally, we find that previously reported cholesterol-GPCR binding motifs are not generalizable, and a new consensus could not be found via residue alignment. The same cholesterol binding patterns hold for a comprehensive dataset including x-ray and cryo-EM structures, indicating that in most cases GPCR side chain environment has little impact.