Site of action of a pentapeptide agonist at the glucagon-like peptide-1 receptor. Insight into a small molecule agonist-binding pocket

https://doi.org/10.1016/j.bmcl.2011.10.065Get rights and content

Abstract

The development of small molecule agonists for class B G protein-coupled receptors (GPCRs) has been quite challenging. With proof-of-concept that exenatide, the parenterally administered peptide agonist of the glucagon-like peptide-1 (GLP1) receptor, is an effective treatment for patients with diabetes mellitus, the development of small molecule agonists could have substantial advantages. We previously reported a lead for small molecule GLP1 receptor agonist development representing the pentapeptide NRTFD. In this work, we have prepared an NRTFD derivative incorporating a photolabile benzoylphenylalanine and used it to define its site of action. This peptide probe was a full agonist with potency similar to NRTFD, which bound specifically and saturably to a single, distinct site within the GLP1 receptor. Peptide mapping using cyanogen bromide and endoproteinase Lys-C cleavage of labeled wild type and M397L mutant receptor constructs identified the site of covalent attachment of NRTFD within the third extracellular loop above the sixth transmembrane segment (TM6). This region is the same as that identified using an analogous photolabile probe based on secretin receptor sequences, and has been shown in mutagenesis studies to be important for natural agonist action of several members of this family. While these observations suggest that small molecule ligands can act at a site bordering the third extracellular loop to activate this class B GPCR, the relationship of this site to the site of action of the amino-terminal end of the natural agonist peptide is unclear.

Section snippets

Acknowledgments

This work was supported by grants from American Diabetes Association (1-08-RA-42) and the National Institutes of Health (DK46577). The authors thank M. L. Augustine and A. M. Ball for excellent technical assistance.

References and notes (20)

  • S.R. Hoare et al.

    Biochem. Pharmacol.

    (2006)
  • J.J. Mallee et al.

    J. Biol. Chem.

    (2002)
  • M. Dong et al.

    J. Biol. Chem.

    (2009)
  • E. ter Haar et al.

    Structure

    (2010)
  • Q. Chen et al.

    J. Biol. Chem.

    (2010)
  • C. Parthier et al.

    Trends Biochem. Sci.

    (2009)
  • M. Dong et al.

    J. Biol. Chem.

    (2011)
  • M. Dong et al.

    J. Biol. Chem.

    (2004)
  • A. Bisello et al.

    J. Biol. Chem.

    (1998)
  • M. Dong et al.

    J. Biol. Chem.

    (2010)
There are more references available in the full text version of this article.

Cited by (6)

View full text