G Protein-Coupled Receptors (GPCRs) represent the largest class of membrane proteins in our genome. They are responsible for communicating extracellular information to the cell in a remarkably wide variety of metabolic processes, from neurotransmission to immune response, from nervous system control to sensory response. Vivid interest in GPCRs, from fundamental and pharmacological points of view, has prompted intense research in cellular, biochemical and structural biology of these receptors. While most structural and biophysical studies have extracted receptors from the plasma membrane using detergent, the biology of these proteins happens in a lipid bilayer. We are investigating how lipids do modulate the structure and the function of GPCRS, with a focus on the β2 adrenergic receptor. We combine pharmacological profiling with biophysical characterization to uncover the basis of this phenomenon.