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Updated: Jun 16, 2026

Ultrastructural Localization of Endogenous LC3 by On-Section Correlative Light-Electron Microscopy
Published on: March 31, 2023
Electron tomography reveals the endoplasmic reticulum as a membrane source for autophagosome formation
Mitsuko Hayashi-Nishino1, Naonobu Fujita, Takeshi Noda
1Department of Cell Membrane Biology, Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan.
Abstract:
The origin and source of autophagosomal membranes are long-standing questions. By electron microscopy, we show that the endoplasmic reticulum (ER) associates with early autophagic structures called isolation membranes (IM) or phagophores in mammalian culture cells. Overexpression of a mutant of Atg4B, which causes defects in autophagosome formation, caused accumulation of ER-IM complexes. Electron tomography revealed the ER-IM complex as a subdomain of the ER forming a cradle encircling the IM, and showed that both ER and isolation membranes are interconnected.
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