GPCR activity is modulated by distinct signals that lead to the stabilization of the active receptor conformation(s). This will be studied and analyzed by the projects grouped in group B. Projects B01 to B04 address the function of specific ligands in peptide GPCRs to elucidate the possibilities and mechanisms of receptor activation as well as its physiological consequences, whereas B05 and B06 address similar issues on aGPCRs. Selective and biased peptide and non-peptide ligands as well as allosteric modulators will be studied and mutagenesis and genetically encoded crosslinkers will be used at the receptor side. Drosophila (B06) and C. elegans (B03/C04) as “easy to manipulate” model organisms will be included for studying the relevance of receptor dynamics in in vivo settings.