Parking Garage Shaped Helix (image) Cell Press Caption The endoplasmic reticulum (ER) is the protein-making factory within cells consisting of tightly stacked sheets of membrane studded with the molecules that make proteins. In a study published July 18th by Cell Press in the journal Cell, researchers have refined a new microscopy imaging method to visualize exactly how the ER sheets are stacked, revealing that the 3D structure of the sheets resembles a parking garage with helical ramps connecting the different levels. This structure allows for the dense packing of ER sheets, maximizing the amount of space available for protein synthesis within the small confines of a cell. Credit Cell, Terasaki et al. Usage Restrictions Credit required 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.