(IMAGE) Institute of Science and Technology Austria Caption Proteins (blue) add onto a filament after binding an energy source (black) inside a cell. Credit Proteins (blue) add onto a filament after binding an energy source (black) inside a cell. © Nicola de Mitri Usage Restrictions Free to use when reporting about ISTA 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.