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Extracellular domain of GLP-1 receptor in complex with exendin-4 variant Gly2Hcs/Thr5HcsExtracellular domain of GLP-1 receptor in complex with exendin-4 variant Gly2Hcs/Thr5Hcs
Structural highlights
Function[GLP1R_HUMAN] This is a receptor for glucagon-like peptide 1. The activity of this receptor is mediated by G proteins which activate adenylyl cyclase. [EXE4_HELSU] Venom protein that mimics the incretin hormone glucagon-like peptide 1 (GLP-1). It stimulates insulin synthesis and secretion, protects against beta-cell apoptosis in response to different insults, and promotes beta-cell proliferation. It also promotes satiety, reduces food intake, reduces fat deposition, reduces body weight and inhibits gastric emptying. Interacts with GLP-1 receptor (GLP1R). Induces hypotension that is mediated by relaxation of cardiac smooth muscle.[1] [2] Publication Abstract from PubMedPeptide agonists acting on the glucagon-like peptide 1 receptor (GLP-1R) promote glucose-dependent insulin release and therefore represent important therapeutic agents for type 2 diabetes (T2D). Previous data indicated that an N-terminal type II beta-turn motif might be an important feature for agonists acting on the GLP-1R. In contrast, recent publications reporting the structure of the full-length GLP-1R have shown the N-terminus of receptor-bound agonists in an alpha-helical conformation. To reconcile these conflicting results, we prepared N-terminally constrained analogues of glucagon-like peptide 1 (GLP-1) and exendin-4 and evaluated their receptor affinity and functionality in vitro; we then examined their crystal structures in complex with the extracellular domain of the GLP-1R and used molecular modeling and molecular dynamics simulations for further investigations. We report that the peptides' N-termini in all determined crystal structures adopted a type II beta-turn conformation, but in vitro potency varied several thousand-fold across the series. Potency correlated better with alpha-helicity in our computational model, although we have found that the energy barrier between the two mentioned conformations is low in our most potent analogues and the flexibility of the N-terminus is highlighted by the dynamics simulations. alpha-Helix or beta-Turn? An Investigation into N-Terminally Constrained Analogues of Glucagon-like Peptide 1 (GLP-1) and Exendin-4.,Oddo A, Mortensen S, Thogersen H, De Maria L, Hennen S, McGuire JN, Kofoed J, Linderoth L, Reedtz-Runge S Biochemistry. 2018 Jun 21. doi: 10.1021/acs.biochem.8b00105. PMID:29877701[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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