title: Fluorescein-Trp25-exendin-4, a biologically active fluorescent probe for the human GLP-1 receptor.
abstract: Exendin-4, a reptilian GLP-1 analogue, has been fluorescently labeled by covalently linking a fluorescein moiety onto the Trp residue yielding fluorescein-Trp25-exendin-4 (FLEX). FLEX is equipotent to GLP-1(7-36)-amide and exendin-4 as an inhibitor of [125I] GLP-1 binding to the human GLP-1 receptor stably expressed in CHO cells, and maintains full biological potency and efficacy as measured by the stimulation of cAMP accumulation in these cells. FLEX binding to CHO/hGLP-1R membranes results in an increase in fluorescence anisotropy. The binding is specific and saturable (Kd = 2.0 +/- 0.4 nM), and GLP-1(7-36)-amide and exendin-4 are equipotent inhibitors of FLEX binding to the human GLP-1 receptor. Thus, FLEX is a potent, biologically active ligand that is useful for the study of the binding and functional characteristics of the human GLP-1 receptor.
authors.affiliation: Department of Molecular Pharmacology and Biochemistry, Merck Research Laboratories, Rahway, NJ 07065, USA.
authors.forename: G G
authors.initials: GG
authors.lastname: Chicchi
authors.forename: M A
authors.initials: MA
authors.lastname: Cascieri
authors.forename: M P
authors.initials: MP
authors.lastname: Graziano
authors.forename: T
authors.initials: T
authors.lastname: Calahan
authors.forename: M R
authors.initials: MR
authors.lastname: Tota
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D005452:Fluoresceins / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D005768:Gastrointestinal Hormones / Q000378:metabolism; D052216:Glucagon-Like Peptide 1; D000067757:Glucagon-Like Peptide-1 Receptor; D006801:Humans; D007700:Kinetics; D010455:Peptides / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D018027:Receptors, Glucagon / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis / Q000378:metabolism*; D014162:Transfection
chemical_list: D005452:Fluoresceins; C000593833:GLP1R protein, human; D005768:Gastrointestinal Hormones; D000067757:Glucagon-Like Peptide-1 Receptor; D010455:Peptides; D018027:Receptors, Glucagon; D011994:Recombinant Proteins; C106578:fluorescein-Trp(25)-exendin-4; D052216:Glucagon-Like Peptide 1; D000242:Cyclic AMP