Structural insights into the extracellular recognition of the human serotonin 2B receptor by an antibody

Significance Highly selective monoclonal antibodies recognizing the extracellular 3D epitope of G protein-coupled receptors represent valuable tools for elucidating receptor function and localization in the cell and show promise for a range of therapeutic applications. Here we present the structure of a complex between the human serotonin 2B receptor, captured in an active-like state, and an antibody Fab fragment, bound to the extracellular side of the receptor. The structure uncovers the mechanisms of receptor activation and of extracellular receptor recognition by antibodies.