title: Key interactions by conserved polar amino acids located at the transmembrane helical boundaries in Class B GPCRs modulate activation, effector specificity and biased signalling in the glucagon-like peptide-1 receptor.
abstract: Class B GPCRs can activate multiple signalling effectors with the potential to exhibit biased agonism in response to ligand stimulation. Previously, we highlighted key TM domain polar amino acids that were crucial for the function of the GLP-1 receptor, a key therapeutic target for diabetes and obesity. Using a combination of mutagenesis, pharmacological characterisation, mathematical and computational molecular modelling, this study identifies additional highly conserved polar residues located towards the TM helical boundaries of Class B GPCRs that are important for GLP-1 receptor stability and/or controlling signalling specificity and biased agonism. This includes (i) three positively charged residues (R3.30227, K4.64288, R5.40310) located at the extracellular boundaries of TMs 3, 4 and 5 that are predicted in molecular models to stabilise extracellular loop 2, a crucial domain for ligand affinity and receptor activation; (ii) a predicted hydrogen bond network between residues located in TMs 2 (R2.46176), 6 (R6.37348) and 7 (N7.61406and E7.63408) at the cytoplasmic face of the receptor that is important for stabilising the inactive receptor and directing signalling specificity, (iii) residues at the bottom of TM 5 (R5.56326) and TM6 (K6.35346and K6.40351) that are crucial for receptor activation and downstream signalling; (iv) residues predicted to be involved in stabilisation of TM4 (N2.52182and Y3.52250) that also influence cell signalling. Collectively, this work expands our understanding of peptide-mediated signalling by the GLP-1 receptor.
authors: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia. Electronic address: denise.wootten@monash.edu.
authors: Denise
authors: D
authors: Wootten
authors: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
authors: Christopher A
authors: CA
authors: Reynolds
authors: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
authors: Kevin J
authors: KJ
authors: Smith
authors: School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.
authors: Juan C
authors: JC
authors: Mobarec
authors: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
authors: Sebastian G B
authors: SG
authors: Furness
authors: Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, AZ 85259, USA.
authors: Laurence J
authors: LJ
authors: Miller
authors: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia.
authors: Arthur
authors: A
authors: Christopoulos
authors: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Victoria 3052, Australia. Electronic address: patrick.sexton@monash.edu.
authors: Patrick M
authors: PM
authors: Sexton
mesh_terms: D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D017124:Conserved Sequence; D003412:Cricetulus; D000067757:Glucagon-Like Peptide-1 Receptor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism*; D054730:Protein Interaction Domains and Motifs; D055550:Protein Stability; D011869:Radioligand Assay; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D040681:Structural Homology, Protein; D000097789:Glucagon-Like Peptide-1 Receptor Agonists
chemical_list: C000593833:GLP1R protein, human; D000067757:Glucagon-Like Peptide-1 Receptor; D008024:Ligands; D050505:Mutant Proteins; D011994:Recombinant Proteins; D000097789:Glucagon-Like Peptide-1 Receptor Agonists
keywords: Biased agonism; Cell signaling; G protein-coupled receptor; Glucagon-like peptide-1 receptor