G-protein-coupled receptor inactivation by an allosteric inverse-agonist antibody

Tomoya Hino, Takatoshi Arakawa, Hiroko Iwanari, Takami Yurugi-Kobayashi, Chiyo Ikeda-Suno, Yoshiko Nakada-Nakura, Osamu Kusano-Arai, Simone Weyand, Tatsuro Shimamura, Norimichi Nomura, Alexander D. Cameron, Takuya Kobayashi, Takao Hamakubo, So Iwata, and Takeshi Murata

G-protein-coupled receptors are the largest class of cell-surface receptors, and these membrane proteins exist in equilibrium between inactive and active states. Conformational changes induced by extracellular ligands binding to G-protein-coupled receptors result in a cellular response through the activation of G proteins. The A2A adenosine receptor (A2AAR) is responsible for regulating blood flow to the cardiac muscle and is important in the regulation of glutamate and dopamine release in the brain. Here we report the raising of a mouse monoclonal antibody against human A2AAR that prevents agonist but not antagonist binding to the extracellular ligand-binding pocket, and describe the structure of A2AAR in complex with the antibody Fab fragment (Fab2838). This structure reveals that Fab2838 recognizes the intracellular surface of A2AAR and that its complementarity-determining region, CDR-H3, penetrates into the receptor. CDR-H3 is located in a similar position to the G-protein carboxy-terminal fragment in the active opsin structure and to CDR-3 of the nanobody in the active β2-adrenergic receptor structure, but locks A2AAR in an inactive conformation. These results suggest a new strategy to modulate the activity of G-protein-coupled receptors.


DOI


Journal: Nature