Switch-Cyclop (IMAGE) University of Würzburg Caption Violet light triggers a signalling chain in the light sensor protein switch-Cyclop, blue or green light stops the chain. At the end, the production of the signalling molecule cGMP is regulated by the enzyme guanylyl cyclase (GC). Credit (Picture: Shiqiang Gao / University of Wuerzburg) Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.