How Enzymes Communicate (IMAGE) University of Freiburg Caption Electro-chemical coupling through protein super complexes: The calcium channel (Cav2) delivers calcium ions (Ca2+) that activate the enzyme NO synthase (NOS) for generation of the messenger NO. Credit Source: Bernd Fakler 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.