LC3 and Autophagy

  • Isei Tanida
  • Takashi Ueno
  • Eiki Kominami
Part of the Methods in Molecular Biology™ book series (MIMB, volume 445)

Summary

Microtubule-associated protein 1A/1B-light chain 3 (LC3) is a soluble protein with a molecular mass of ∼17 kDa that is distributed ubiquitously in mammalian tissues and cultured cells. During autophagy, autophagosomes engulf cytoplasmic components, including cytosolic proteins and organelles. Concomitantly, a cytosolic form of LC3 (LC3-I) is conjugated to phosphatidylethanolamine to form LC3-phosphatidylethanolamine conjugate (LC3-II), which is recruited to autophagosomal membranes. Autophagosomes fuse with lysosomes to form autolysosomes, and intra-autophagosomal components are degraded by lysosomal hydrolases. At the same time, LC3-II in autolysosomal lumen is degraded. Thus, lysosomal turnover of the autophagosomal marker LC3-II reflects starvation-induced autophagic activity, and detecting LC3 by immunoblotting or immunofluorescence has become a reliable method for monitoring autophagy and autophagy-related processes, including autophagic cell death. Here we describe basic protocols to assay for endogenous LC3-II by immunoblotting, immunoprecipitation, and immunofluorescence.

Key Words

LC3 lipidation ubiquitylation-like reaction autophagosome autolysosome autophagy ATG conjugation system 

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Copyright information

© Humana Press, a part of Springer Science+Business Media, LLC 2008

Authors and Affiliations

  • Isei Tanida
    • 1
  • Takashi Ueno
    • 1
  • Eiki Kominami
    • 1
  1. 1.Department of BiochemistryJuntendo University School of MedicineBunkyo-kuJapan

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