Photoprobe Peptides to Map the Interactions of Angiotensin II with its Receptor AT1

摘要

Seven transmembrane domains (TMDs) G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors and are implicated in various pathologies. In fact, those proteins are privileged targets in pharmacotherapy since approximatively 50% of all current market drugs act via these receptors. The rational design of drugs targeting GPCRs requires a 3D molecular-based knowledge of those proteins that may be acquired by identification of ligand-receptor interactions through photoaffinity labeling [1]. This approach allows to directly map the ligand-receptor interface by covalent bonding of the radio-labeled photoprobe ligand within the immediate molecular surroundings of its cognate receptor. This information may then be used in conjunction with computational molecular modeling procedures, based on the X-ray crystallography of bovine rhodopsin, to build and validate homology molecular models of receptors with ligand [2]. In the present contribution, we have combined a photoaffinity labeling approach with an X → Methionine (Met) mutagenesis strategy to study the molecular structure as well as the activation mechanism of the human angiotensin II (AngII) type 1 receptor (hATi) following the binding of the agonist Angll hormone. AT1 is a typical class-A, rhodopsin-like GPCR, which mediates virtually all of the known physiological action of Angll, it is responsible for cardiovascular and electrolyte homeostasis [3].