title: Refinement of glucagon-like peptide 1 docking to its intact receptor using mid-region photolabile probes and molecular modeling.
abstract: The glucagon-like peptide 1 (GLP1) receptor is an important drug target within the B family of G protein-coupled receptors. Its natural agonist ligand, GLP1, has incretin-like actions and the receptor is a recognized target for management of type 2 diabetes mellitus. Despite recent solution of the structure of the amino terminus of the GLP1 receptor and several close family members, the molecular basis for GLP1 binding to and activation of the intact receptor remains unclear. We previously demonstrated molecular approximations between amino- and carboxyl-terminal residues of GLP1 and its receptor. In this work, we study spatial approximations with the mid-region of this peptide to gain insights into the orientation of the intact receptor and the ligand-receptor complex. We have prepared two new photolabile probes incorporating a p-benzoyl-l-phenylalanine into positions 16 and 20 of GLP1(7-36). Both probes bound to the GLP1 receptor specifically and with high affinity. These were each fully efficacious agonists, stimulating cAMP accumulation in receptor-bearing CHO cells in a concentration-dependent manner. Each probe specifically labeled a single receptor site. Protease cleavage and radiochemical sequencing identified receptor residue Leu(141) above transmembrane segment one as its site of labeling for the position 16 probe, whereas the position 20 probe labeled receptor residue Trp(297) within the second extracellular loop. Establishing ligand residue approximation with this loop region is unique among family members and may help to orient the receptor amino-terminal domain relative to its helical bundle region.
authors: Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Scottsdale, Arizona 85259, USA. miller@mayo.edu
authors: Laurence J
authors: LJ
authors: Miller
authors: Quan
authors: Q
authors: Chen
authors: Polo C-H
authors: PC
authors: Lam
authors: Delia I
authors: DI
authors: Pinon
authors: Patrick M
authors: PM
authors: Sexton
authors: Ruben
authors: R
authors: Abagyan
authors: Maoqing
authors: M
authors: Dong
mesh_terms: D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D052216:Glucagon-Like Peptide 1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000067757:Glucagon-Like Peptide-1 Receptor; D006801:Humans; D008958:Models, Molecular; D015335:Molecular Probes / Q000737:chemistry*; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D018027:Receptors, Glucagon / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: C000593833:GLP1R protein, human; D000067757:Glucagon-Like Peptide-1 Receptor; D015335:Molecular Probes; D018027:Receptors, Glucagon; D052216:Glucagon-Like Peptide 1