GtACR2 (IMAGE) Okayama University Caption Four amino acid mutations were introduced in GtACR2 to engineer a new variant protein. The variant can be controlled to induce and stop inward chloride currents using green and red light, respectively, which would turn the neural silencing effects "on" and "off." A photograph of purified proteins is also shown above. Credit 2020 Okayama University Usage Restrictions The image may only be used with appropriate caption or credit 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.