Plants, fungi, and bacteria perceive blue light through photoreceptors. Light triggers photochemical reactions that control vital processes in cells. Researchers at the University of Bayreuth have now discovered that certain receptors do not necessarily require a specific glutamine, which was previously thought to be indispensable. Even without this glutamine, blue light can trigger crucial control signals in many organisms, albeit often with reduced efficiency. The results presented in Nature Communications make an important contribution to understanding the mechanisms of photoreceptors and their applications.