Researchers unveil new details of how cells in a living organism process stimuli. So-called G-proteins, which help conduct external stimuli that reach a cell into its interior, play a central role here. For the first time, the study shows which parts of the G-proteins are vital for their function. Researchers from the Paul Scherrer Institute PSI, ETH Zurich, the pharmaceutical company Roche and the British MRC Laboratory of Molecular Biology report their results in the journals Nature and Nature Structural and Molecular Biology.