title: VPAC1 receptor binding site: contribution of photoaffinity labeling approach.
abstract: The vasoactive intestinal peptide (VIP) is a prominent 28 aminoacid neuropeptide with wide distribution in both central and peripheral nervous systems, where it plays important regulatory role in many physiological processes. VIP has a large spectrum of biological functions including exocrine secretions, hormone release, foetal development, immune response and also exerts beneficial effect in neuro-degenerative and inflammatory diseases. Few years ago, it has been shown that VIP can be a promising anti-inflammatory agent. VIP mechanisms of action implicate two sub-types of receptors (VPAC1 and VPAC2) which are members of class B receptors belonging to the super-family of G protein-coupled receptor (GPCR). Because, VPAC1 receptor plays an important role in the modulation of the ant-inflammatory response and represent an archetype of class B GPCR, we have extensively studied the structure-function relationship of this receptor, which allowed us to define the molecular basis of that receptor in term of affinity, specificity, desensitization and coupling to adenylyl cyclase. Those studies showed the crucial role of the N-terminal ectodomain (N-ted) of VPAC1 receptor in VIP binding. Using different techniques including photoaffinity labeling, NMR, molecular modeling and molecular dynamic simulation, it has been possible to define how VIP interacts with its receptor. We have shown that most of the VIP molecule, 1-28 (alpha-helix) sequence, tightly binds the N-ted part of the receptor which is himself structured as a <<Sushi>> domain. In contrast, the N-terminal part of the specific antagonist PG97-269 is in physical contact with the N-ted but in different region. These studies define the molecular mechanism implicated in the activation of class B VPAC1 receptor and should allow the development of new VIP pharmacology using rational synthesis of agonist molecules.
authors.affiliation: INSERM 773, Centre de Recherche Biomédicale Bichat Beaujon (CRB3), Faculté de Médecine Xavier Bichat, Université Paris 7, 75870 Paris Cedex 18, France. alain.couvineau@inserm.fr
authors.forename: A
authors.initials: A
authors.lastname: Couvineau
authors.forename: E
authors.initials: E
authors.lastname: Ceraudo
authors.forename: Y-V
authors.initials: YV
authors.lastname: Tan
authors.forename: M
authors.initials: M
authors.lastname: Laburthe
mesh_terms: D000818:Animals; D001665:Binding Sites; D007249:Inflammation / Q000378:metabolism*; D019920:Photoaffinity Labels / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism*
chemical_list: D019920:Photoaffinity Labels; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D014660:Vasoactive Intestinal Peptide