Acylation of the incretin peptide exendin-4 directly impacts GLP-1 receptor signalling and trafficking

Research output: Contribution to journalArticlepeer-review


  • Maria Lucey
  • Tanyel Ashik
  • Amaara Marzook
  • Yifan Wang
  • Joelle Goulding
  • Atsuro Oishi
  • Johannes Broichhagen
  • James Minnion
  • Yuval Elani
  • Ralf Jockers
  • Steven J Briddon
  • Stephen R Bloom
  • Alejandra Tomas
  • Ben Jones

Colleges, School and Institutes


The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor and mainstay therapeutic target for the treatment of type 2 diabetes and obesity. Recent reports have highlighted how biased agonism at the GLP-1R affects sustained glucose-stimulated insulin secretion through avoidance of desensitisation and downregulation. A number of GLP-1R agonists (GLP-1RAs) feature a fatty acid moiety to prolong their pharmacokinetics via increased albumin binding, but the potential for these chemical changes to influence GLP-1R function has rarely been investigated beyond potency assessments for cyclic adenosine monophosphate (cAMP). Here we directly compare the prototypical GLP-1RA exendin-4 with its C-terminally acylated analogue, exendin-4-C16. We examine relative propensities of each ligand to recruit and activate G proteins and β-arrestins, endocytic and post-endocytic trafficking profiles, and interactions with model and cellular membranes in HEK293 and HEK293T cells. Both ligands had similar cAMP potency but exendin-4-C16 showed ~2.5-fold bias towards G protein recruitment and a ~60% reduction in β-arrestin-2 recruitment efficacy compared to exendin-4, as well as reduced GLP-1R endocytosis and preferential targeting towards recycling pathways. These effects were associated with reduced movement of the GLP-1R extracellular domain measured using a conformational biosensor approach, and a ~70% increase in insulin secretion in INS-1 832/3 cells. Interactions with plasma membrane lipids were enhanced by the acyl chain. Exendin-4-C16 showed extensive albumin binding and was highly effective for lowering of blood glucose in mice over at least 72 hours. Our study highlights the importance of a broad approach to the evaluation of GLP-1RA pharmacology.

Significance Statement: Acylation is a common strategy to enhance the pharmacokinetics of peptide-based drugs. Our work shows how acylation can also affect various other pharmacological parameters, including biased agonism, receptor trafficking and interactions with the plasma membrane, which may be therapeutically important.

Bibliographic note

Final Version of Record not yet available as of 21/09/2021.


Original languageEnglish
JournalMolecular Pharmacology
Publication statusAccepted/In press - 12 Jul 2021


  • Biased agonism, G protein coupled signaling, GLP1, g protein-coupled receptors (GPCRS), receptor trafficking