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EMBO J. 2000 Nov 1;19(21):5720-8.

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

Author information

1
Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, PRESTO, Japan.

Erratum in

  • EMBO J. 2003 Sep 1;22(17):4577.

Abstract

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.

PMID:
11060023
PMCID:
PMC305793
DOI:
10.1093/emboj/19.21.5720
[Indexed for MEDLINE]
Free PMC Article

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