A subdomain of the endoplasmic reticulum forms a cradle for autophagosome formation

Nat Cell Biol. 2009 Dec;11(12):1433-7. doi: 10.1038/ncb1991. Epub 2009 Nov 8.


Autophagy is a bulk degradation process in eukaryotic cells and has fundamental roles in cellular homeostasis.The origin and source of autophagosomal membranes are long-standing questions in the field. Using electron microscopy, we show that, in mammalian culture cells, the endoplasmic reticulum (ER) associates with early autophagic structures called isolation membranes (IMs). Overexpression of an Atg4B mutant, which causes defects in autophagosome formation, induces the accumulation of ER-IM complexes. Electron tomography revealed that the ER-IM complex appears as a subdomain of the ER that formed a cradle encircling the IM, and showed that both ER and isolation membranes are interconnected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy*
  • Autophagy-Related Proteins
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Cell Line
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum / ultrastructure*
  • Humans
  • Mice
  • Microscopy, Electron, Transmission
  • Microscopy, Immunoelectron
  • Phagosomes / metabolism
  • Phagosomes / ultrastructure*


  • Autophagy-Related Proteins
  • Carrier Proteins
  • ZFYVE1 protein, human
  • ATG4B protein, human
  • Cysteine Endopeptidases