Head of Mediator Molecule (IMAGE) Indiana University School of Medicine Caption Scientists have deciphered the structure of an essential part of Mediator, a complex molecular machine that plays a vital role in regulating the transcription of DNA. Credit Indiana University School of Medicine 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.