Today, proteins that can be controlled with light are a widely used tool in research to specifically switch certain functions on and off in living organisms. Channelrhodopsins are often used for the technique known as optogenetics: When exposed to light, these proteins open a pore in the cell membrane through which ions can flow in; this is how nerve cells can be activated. A team from the Centre for Protein Diagnostics (PRODI) at Ruhr-Universität Bochum has now used spectroscopy to discover a universal functional mechanism of channelrhodopsins that determines their efficiency as a channel and thus as an optogenetic tool. The researchers led by Professor Klaus Gerwert describe the results in the journal Communications Biology of 14 May 2021. They expect that the findings will help tailor more efficient optogenetic tools in the future.