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Spatial proximity between the VPAC1 receptor and the amino terminus of agonist and antagonist peptides reveals distinct sites of interaction

par Ceraudo, Emilie ;Hierso, Régine;Tan, Yossan-Var;Murail, Samuel;Rouyer-Fessard, Christiane;Nicole, Pascal;Robert, Jean-Claude;Jamin, Nadège;Neumann, Jean-Michel;Robberecht, Patrick ;Laburthe, Marc;Couvineau, Alain
Référence The FASEB journal, 26, 5, page (2060-2071)
Publication Publié, 2012-05

Article révisé par les pairs

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Résumé :

Vasoactive intestinal peptide (VIP) plays a major role in pathophysiology. Our previous studies demonstrated that the VIP sequence 6-28 interacts with the N-terminal ectodomain (N-ted) of its receptor, VPAC1. Probes for VIP and receptor antagonist PG97- 269 were synthesized with a photolabile residue/Bpa at various positions and used to explore spatial proximity with VPAC1. PG97-269 probes with Bpa at position 0, 6, and 24 behaved as high-affinity receptor antagonists (Ki=12, 9, and 7 nM, respectively). Photolabeling experiments revealed that the [Bpa0]-VIP probe was in physical contact with VPAC1 Q135, while [Bpa0]-PG97- 269 was covalently bound to G62 residue of N-ted, indicating different binding sites. In contrast, photolabeling with [Bpa6]- and [Bpa 24]-PG97-269 showed that the distal domains of PG97-269 interacted with N-ted, as we previously showed for VIP. Substitution with alanine of the K143, T144, and T147 residues located in the first transmembrane domain of VPAC1 induced a loss of receptor affinity (IC 50=1035, 874, and 2070 nM, respectively), and pharmacological studies using VIP2-28 indicated that these three residues play an important role in VPAC1 interaction with the first histidine residue of VIP. These data demonstrate that VIP and PG97-269 bind to distinct domains of VPAC1. © FASEB.