Photoaffinity scanning in the mapping of the peptide receptor interface of class II G protein—coupled receptors

Abstract

The family of G protein-coupled receptors constitutes about 50% of the therapeutic drug targets used in clinical medicine today, although the mechanisms of ligand binding, activation and signal transduction for G protein-coupled receptors are not yet well defined. This review discusses ongoing research using the photoaffinity scanning method to map the bimolecular interface between class II G protein-coupled receptors and their ligands. Furthermore the available computer model of class II peptide ligand docking into the receptor, based on the positional constraints imposed by the photoaffinity scanning analyses, will be discussed briefly. The ultimate goal of these efforts is to understand the molecular basis of receptor binding and therefore to generate a template for rational drug design.

Residue 17 of Sauvagine Cross-links to the First Transmembrane Domain of Corticotropin-releasing Factor Receptor 1 (CRFR1)

“…The crystal structure of the PTH1R extracellular domain-PTH(15-34) complexes provides direct evidence for the model that the C-terminal domain of the ligand binds to the N terminus of the receptor, thus positioning the N terminus of the ligand at a favorable distance to allosterically activate the J-domain of the receptor (52). Therefore, it is interesting to compare the data from photoaffinity cross-linking of PTH1R (22)(23)(24)(25)(53)(54)(55)(56)(57)(58)(59)(60) with those of CRFR1. Similar to our finding that residues 16 and 17 of sauvagine cross-link to the J-domain of CRFR1, residues within the C terminus of PTH , such as 19 and 27, are reported to cross-link to the second transmembrane domain and within the first extracellular loop, respectively; both are within the J-domain of PTH1R (58).…”

Photoaffinity Cross-Linking of the Corticotropin-Releasing Factor Receptor Type 1 with Photoreactive Urocortin Analogues

“…Klose et al (24) reported on the binding behavior of N-terminally truncated urocortins to soluble receptor N-termini. They proposed a three-domain binding model, in that the urocortin C-terminus (aa [32][33][34][35][36][37][38][39][40] and the N-terminal part (aa 1-21) are organized as two segregated binding domains. Moreover, the N-terminal domain (aa 1-21) also consists of two segregated sites; one is responsible for receptor activation (aa 1-11) and the other (aa [12][13][14][15][16][17][18][19][20][21] for ligand binding at the receptor N-terminus.…”

Ligand-Receptor Interactions at the Parathyroid Hormone Receptors: Subtype Binding Selectivity Is Mediated via an Interaction between Residue 23 on the Ligand and Residue 41 on the Receptor

“…This first interaction positions the N-terminal region of the peptide such that it activates the receptor via a second interaction with the receptor's juxtamembrane "core" domain, comprising the transmembrane helices and connecting loops. The nature of the first interaction has been investigated via a number of mutagenic and cross-linking studies (Mannstadt et al, 1998;Gensure et al, 2001;Pham and Sexton, 2004) and more recently has been the focus of several structural studies that defined the structures of the peptidebound N domains of the receptors for corticotropin-releasing factor, pituitary adenylyl cyclase-activating polypeptide, glucose-dependent insulinotropic peptide (GIP), glucagon-like peptide-1 (GLP-1) and, very recently, PTH itself (Grace et al, …”