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<p>The ER-associated degradation (ERAD) pathway retrotranslocates misfolded proteins from the ER lumen to the cytoplasm for proteasomal degradation. Derlin-1 and p97 are central to this process, forming a canonical 4:6 complex with tetrameric Derlin-1. Using cryo-electron microscopy, we identify a novel human Derlin-1/p97 complex with a 6:6 stoichiometry, where hexameric Derlin-1 assembles as three dimers. This hexameric channel forms a significantly larger trans-ER membrane tunnel, potentially accommodating bulkier substrates. Structural comparisons revealed conformational flexibility in Derlin-1, suggesting the “U”-shaped tetramer may act as an intermediate in hexamer formation. The formation of this hexameric channel is mediated by interactions with p97 and appears dependent on p97’s ATPase activity, which provides the driving force for the transition between the tetrameric channel conformation to the intermediate “U”-shaped conformation. These findings highlight the dynamic nature of the Derlin-1/p97 complex and its implications for understanding ERAD retrotranslocation.</p>

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Cryo-EM structure of the human Derlin-1/p97 complex reveals a hexameric channel in ERAD

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年10月17日

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  • Qian Wang,
  • Deqiang Yao,
  • Bing Rao,
  • Ying Xia,
  • Wenguo Li,
  • Shaobai Li,
  • Mi Cao,
  • Yafeng Shen,
  • An Qin,
  • Yu Cao

摘要

The ER-associated degradation (ERAD) pathway retrotranslocates misfolded proteins from the ER lumen to the cytoplasm for proteasomal degradation. Derlin-1 and p97 are central to this process, forming a canonical 4:6 complex with tetrameric Derlin-1. Using cryo-electron microscopy, we identify a novel human Derlin-1/p97 complex with a 6:6 stoichiometry, where hexameric Derlin-1 assembles as three dimers. This hexameric channel forms a significantly larger trans-ER membrane tunnel, potentially accommodating bulkier substrates. Structural comparisons revealed conformational flexibility in Derlin-1, suggesting the “U”-shaped tetramer may act as an intermediate in hexamer formation. The formation of this hexameric channel is mediated by interactions with p97 and appears dependent on p97’s ATPase activity, which provides the driving force for the transition between the tetrameric channel conformation to the intermediate “U”-shaped conformation. These findings highlight the dynamic nature of the Derlin-1/p97 complex and its implications for understanding ERAD retrotranslocation.