Ribbon Diagram Comparison (image) University of Maryland Share Print E-Mail Caption This pair of 'ribbon diagram' images compares the three-dimensional structures of two closely related proteins, determined by X-ray crystallography: (L) the HAP2 protein from the single-celled alga Chlamydomonas reinhardtii and (R) the fusion protein from dengue virus. Both proteins are necessary for fusion with a cell membrane, enabling both sexual reproduction (via the fusion of sex cells) and viral invasion of a cell, respectively. New research suggests that these proteins are functionally identical and evolved early in the history of life on Earth. Credit Felix Rey, Pasteur Institute Usage Restrictions None Share Print E-Mail 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.