The aim of optogenetics is to control genetically modified cells using light. A team of Graz scientists led by Andreas Winkler from the Institute of Biochemistry at TU Graz have set a milestone in the future development of novel red-light regulated optogenetic tools for targeted cell stimulation. For the first time ever, they were able to observe molecular principles of sensor-effector coupling in the full-length structure of a red-light responsive protein and describe detailed mechanisms of signal transmission over long distances at a molecular level. The results of the research have been published in the open access journal Science Advances.