The isolated N-terminal extracellular domain of the glucagon-like peptide-1 (GLP)-1 receptor has intrinsic binding activity.
The glucagon-like peptide 1 (7-37)/(7-36) amide (GLP-1) receptor belongs to a new subclass of seven transmembrane domain, G-protein coupled receptors comprising several receptors for peptide hormones. The receptors of this family share many common motifs including a relatively large N-terminal extracellular domain. The GLP-1 receptor is presently attracting much attention, since it is the target protein of the antidiabetic gut hormone GLP-1. To establish the functional significance of the N-terminal part of the GLP-1 receptor for ligand binding, the extracellular domain was isolated and purified. Utilizing CHL cells expressing the cloned GLP-1 receptor, we demonstrate that the isolated, solubilized N-terminal part of the receptor protein competes for GLP-1 binding with the intact wild-type receptor. Moreover, in cross-linking experiments radiolabeled GLP-1 was covalently attached to the isolated N-terminus, thereby demonstrating direct physical interaction of both components. By Western blot analysis two specific bands were detectable, representing the N-terminal receptor protein in the presence or absence of bound ligand. These data underline the significance of the N-terminal domain of the GLP-1 receptor for ligand binding.
Wilmen
A
A
Clinical Research Group for Gastrointestinal Endocrinology, Philipps-University of Marburg, Germany.
Göke
B
B
Göke
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D006224:Cricetinae; D005934:Glucagon / Q000378:metabolism; D052216:Glucagon-Like Peptide 1; D000067757:Glucagon-Like Peptide-1 Receptor; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000378:metabolism; D011487:Protein Conformation; D011498:Protein Precursors / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D018027:Receptors, Glucagon / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility
C000593835:Glp1r protein, rat; D000067757:Glucagon-Like Peptide-1 Receptor; D010446:Peptide Fragments; D011498:Protein Precursors; D018027:Receptors, Glucagon; D011994:Recombinant Proteins; D052216:Glucagon-Like Peptide 1; D005934:Glucagon