XStacked endoplasmic reticulum sheets are connected by helicoidal membrane motifs

Mark Terasaki*, Tom Shemesh, Narayanan Kasthuri, Robin W. Klemm, Richard Schalek, Kenneth J. Hayworth, Arthur R. Hand, Maya Yankova, Greg Huber, Jeff W. Lichtman, Tom A. Rapoport, Michael M. Kozlov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

174 Scopus citations

Abstract

The endoplasmic reticulum (ER) often forms stacked membrane sheets, an arrangement that is likely required to accommodate a maximum of membrane-bound polysomes for secretory protein synthesis. How sheets are stacked is unknown. Here, we used improved staining and automated ultrathin sectioning electron microscopy methods to analyze stacked ER sheets in neuronal cells and secretory salivary gland cells of mice. Our results show that stacked ER sheets form a continuous membrane system in which the sheets are connected by twisted membrane surfaces with helical edges of left- or right-handedness. The three-dimensional structure of tightly stacked ER sheets resembles a parking garage, in which the different levels are connected by helicoidal ramps. A theoretical model explains the experimental observations and indicates that the structure corresponds to a minimum of elastic energy of sheet edges and surfaces. The structure allows the dense packing of ER sheets in the restricted space of a cell.

Original languageEnglish
Pages (from-to)285
Number of pages1
JournalCell
Volume154
Issue number2
DOIs
StatePublished - 18 Jul 2013

Funding

FundersFunder number
Joseph Klafter Chair in Biophysics
Marie Curie Network
National Science FoundationNSF PHY11-25915
National Institute of Biomedical Imaging and BioengineeringR01EB016411
Israel Science Foundation

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