Cotranslocational degradation protects the stressed endoplasmic reticulum from protein overload - PubMed (original) (raw)

. 2006 Aug 25;126(4):727-39.

doi: 10.1016/j.cell.2006.06.051.

Chi Yun, Edward A Fisher, Nicola Kreglinger, Gert Kreibich, Miho Oyadomari, Heather P Harding, Alan G Goodman, Hanna Harant, Jennifer L Garrison, Jack Taunton, Michael G Katze, David Ron

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Cotranslocational degradation protects the stressed endoplasmic reticulum from protein overload

Seiichi Oyadomari et al. Cell. 2006.

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Abstract

The ER's capacity to process proteins is limited, and stress caused by accumulation of unfolded and misfolded proteins (ER stress) contributes to human disease. ER stress elicits the unfolded protein response (UPR), whose components attenuate protein synthesis, increase folding capacity, and enhance misfolded protein degradation. Here, we report that P58(IPK)/DNAJC3, a UPR-responsive gene previously implicated in translational control, encodes a cytosolic cochaperone that associates with the ER protein translocation channel Sec61. P58(IPK) recruits HSP70 chaperones to the cytosolic face of Sec61 and can be crosslinked to proteins entering the ER that are delayed at the translocon. Proteasome-mediated cytosolic degradation of translocating proteins delayed at Sec61 is cochaperone dependent. In P58(IPK-/-) mice, cells with a high secretory burden are markedly compromised in their ability to cope with ER stress. Thus, P58(IPK) is a key mediator of cotranslocational ER protein degradation, and this process likely contributes to ER homeostasis in stressed cells.

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