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  • The EMBO Journal (2000) 19, 5720 - 5728
  • doi:10.1093/emboj/19.21.5720



There is a Corrigendum (September 2003) associated with this Article.

LC3, a mammalian homologue of yeast Apg8p, is localized in autophagosome membranes after processing

Yukiko Kabeya1, Noboru Mizushima1,2, Takashi Ueno3, Akitsugu Yamamoto4, Takayoshi Kirisako1,5, Takeshi Noda1,5, Eiki Kominami3, Yoshinori Ohsumi1,5 and Tamotsu Yoshimori1,5

  1. Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan
  2. PRESTO, Japan Science and Technology Corporation (JST), Kawaguchi 332-0012, Japan
  3. Department of Biochemistry, Juntendo University School of Medicine, Hongo, Tokyo 113-8421, Japan
  4. Department of Physiology, Kansai Medical University, Moriguchi 570-0074 Japan
  5. Department of Molecular Biomechanics, School of Life Science, The Graduate University for Advanced Studies, Hayama 240-0193, Japan

Correspondence to:

Tamotsu Yoshimori, E-mail: yosimori@nibb.ac.jp

Received 6 March 2000; Accepted 11 September 2000; Revised 29 August 2000

Little is known about the protein constituents of autophagosome membranes in mammalian cells. Here we demonstrate that the rat microtubule-associated protein 1 light chain 3 (LC3), a homologue of Apg8p essential for autophagy in yeast, is associated to the autophagosome membranes after processing. Two forms of LC3, called LC3-I and -II, were produced post-translationally in various cells. LC3-I is cytosolic, whereas LC3-II is membrane bound. The autophagic vacuole fraction prepared from starved rat liver was enriched with LC3-II. Immunoelectron microscopy on LC3 revealed specific labelling of autophagosome membranes in addition to the cytoplasmic labelling. LC3-II was present both inside and outside of autophagosomes. Mutational analyses suggest that LC3-I is formed by the removal of the C-terminal 22 amino acids from newly synthesized LC3, followed by the conversion of a fraction of LC3-I into LC3-II. The amount of LC3-II is correlated with the extent of autophagosome formation. LC3-II is the first mammalian protein identified that specifically associates with autophagosome membranes.

  • Keywords:

    • APG,
    • autophagosomes,
    • autophagy,
    • mammalian homologue,
    • protein cleavage