Journal Article Forcible destruction of severely misfolded mammalian glycoproteins by the non-glycoprotein ERAD pathway.

Ninagawa, Satoshi  ,  Okada, Tetsuya  ,  Sumitomo, Yoshiki  ,  Horimoto, Satoshi  ,  Sugimoto, Takehiro  ,  Ishikawa, Tokiro  ,  Takeda, Shunichi  ,  Yamamoto, Takashi  ,  Suzuki, Tadashi  ,  Kamiya, Yukiko  ,  Kato, Koichi  ,  Mori, Kazutoshi

211 ( 4 )  , pp.775 - 784 , 2015-11-16 , Rockefeller University Press
シビアな構造異常糖タンパク質が出現すると手順を踏まずに強制分解 -酵母にはない高等動物特有の小胞体糖タンパク質分解システムの解明-. 京都大学プレスリリース. 2015-11-20.
Glycoproteins and non-glycoproteins possessing unfolded/misfolded parts in their luminal regions are cleared from the endoplasmic reticulum (ER) by ER-associated degradation (ERAD)-L with distinct mechanisms. Two-step mannose trimming from Man9GlcNAc2 is crucial in the ERAD-L of glycoproteins. We recently showed that this process is initiated by EDEM2 and completed by EDEM3/EDEM1. Here, we constructed chicken and human cells simultaneously deficient in EDEM1/2/3 and analyzed the fates of four ERAD-L substrates containing three potential N-glycosylation sites. We found that native but unstable or somewhat unfolded glycoproteins, such as ATF6α, ATF6α(C), CD3-δ-ΔTM, and EMC1, were stabilized in EDEM1/2/3 triple knockout cells. In marked contrast, degradation of severely misfolded glycoproteins, such as null Hong Kong (NHK) and deletion or insertion mutants of ATF6α(C), CD3-δ-ΔTM, and EMC1, was delayed only at early chase periods, but they were eventually degraded as in wild-type cells. Thus, higher eukaryotes are able to extract severely misfolded glycoproteins from glycoprotein ERAD and target them to the non-glycoprotein ERAD pathway to maintain the homeostasis of the ER.

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