LAUSR

G protein-coupled receptors (GPCRs) are the largest family of membrane protein playing an important role in cellular signal transduction. GPCRs interact with different molecules acting as ligands capable to trigger responses on signaling pathway. Those molecules present specific binding profiles in which, usually, are determined by methods based on radioactive labeled ligands. Here we present an alternative method based on time-resolved fluorescent labeled ligand, specific customized for angiotensin II receptors (AGTR1 and AGTR2) and kinin receptors (BDKRB1 and BDKRB2) wherein, their natural ligands were labeled with the lanthanide europium to generate the Eu3+-N1-DTT-ligands (AngII, BK, and DBK). Competitive binding profile is determined with a fixed concentration of labeled ligand competing with variable concentrations (10-5 to 10-12) of unlabeled ligand. This method is capable to determine binding profiles with comparable results with traditional one and present a reliable alternative to radioactive based methods usage.