Crystal Structure of GtCPES (IMAGE) Ruhr-University Bochum Caption This image shows the atomic structure of the GtCPES protein in its monomeric (left) and dimeric (right) form, which has been solved by X-ray structural analysis. GtCPES forms a barrel-like structure, which is closed at the bottom and open at the top. Inside the barrel, molecules such as phycoerythrobilin can be bound and transported. Credit Kristina Overkamp 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.