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Apg10p, a novel protein‐conjugating enzyme essential for autophagy in yeast

Takahiro Shintani, Noboru Mizushima, Yoko Ogawa, Akira Matsuura, Takeshi Noda, Yoshinori Ohsumi

Author Affiliations

  1. Takahiro Shintani1,
  2. Noboru Mizushima1,
  3. Yoko Ogawa2,
  4. Akira Matsuura3,
  5. Takeshi Noda1 and
  6. Yoshinori Ohsumi*,1
  1. 1 Department of Cell Biology, National Institute for Basic Biology, Okazaki, 444‐8585, Japan
  2. 2 Present address: Department of Neurobiology, Graduate School of Medicine, The University of Tokyo, Tokyo, 113‐0033, Japan
  3. 3 Present address: Department of Life Science, Tokyo Institute of Technology, Yokohama, 226‐8501, Japan
  1. *Corresponding author. E-mail: yohsumi{at}nibb.ac.jp
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Abstract

Autophagy is a cellular process for bulk degradation of cytoplasmic components. The attachment of Apg12p, a modifier with no significant similarity to ubiquitin, to Apg5p is crucial for autophagy in yeast. This reaction proceeds in a ubiquitination‐like manner, and requires Apg7p and Apg10p. Apg7p exhibits a considerable similarity to ubiquitin‐activating enzyme (E1) and is found to activate Apg12p with ATP hydrolysis. Apg10p, on the other hand, shows no significant similarity to other proteins whose functions are known. Here, we show that after activation by Apg7p, Apg12p is transferred to the Cys‐133 residue of Apg10p to form an Apg12p–Apg10p thioester. Cells expressing Apg10pC133S do not generate the Apg12p–Apg5p conjugate, which leads to defects in autophagy and cytoplasm‐to‐vacuole targeting of aminopeptidase I. These findings indicate that Apg10p is a new type of protein‐conjugating enzyme that functions in the Apg12p–Apg5p conjugation pathway.

  • Received June 21, 1999.
  • Revision received August 2, 1999.
  • Accepted August 11, 1999.
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