Multiple endoplasmic reticulum-associated pathways degrade mutant yeast carboxypeptidase Y in mammalian cells
Multiple endoplasmic reticulum-associated pathways degrade mutant yeast carboxypeptidase Y in mammalian cells
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DOI：
10.1074/jbc.m302979200
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发表时间：
2003-11-21
影响因子：
4.8
通讯作者：
Helenius, A
中科院分区：
文献类型：
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作者：
Mancini, R;Aebi, M;Helenius, A
错误折叠和未组装蛋白的内质网（ER）相关降解（ERAD）降解已被证明主要通过泛素-蛋白酶体途径在蛋白质转运到细胞质溶胶后发生。最近的研究揭示了n -链聚糖在ERAD靶向异常糖蛋白中的作用。为了进一步表征哺乳动物细胞ERAD过程中底物识别和分选的分子基础，我们在CHO细胞中表达了酵母羧肽酶Y （CPY*）突变体。CPY*以非聚合形式保留在ER中，并在45分钟的滞后期后降解。降解主要通过蛋白酶体独立的非溶酶体途径进行。内质网甘露糖苷酶I的抑制剂kifunenine通过替代途径阻断了降解，但不影响降解的蛋白酶体部分。抑制葡萄糖修剪后，消除了初始滞后期，从而加速了降解。我们的研究结果表明，尽管蛋白酶体是ERAD的主要参与者，但哺乳动物细胞中存在其他途径，并且可以在糖蛋白和非糖蛋白的处理中发挥重要作用。
The degradation of misfolded and unassembled proteins by the endoplasmic reticulum (ER)-associated degradation (ERAD) has been shown to occur mainly through the ubiquitin-proteasome pathway after transport of the protein to the cytosol. Recent work has revealed a role for N-linked glycans in targeting aberrant glycoproteins to ERAD. To further characterize the molecular basis of substrate recognition and sorting during ERAD in mammalian cells, we expressed a mutant yeast carboxypeptidase Y (CPY*) in CHO cells. CPY* was retained in the ER in un-aggregated form, and degraded after a 45-min lag period. Degradation was predominantly by a proteasome-independent, non-lysosomal pathway. The inhibitor of ER mannosidase I, kifunensine, blocked the degradation by the alternate pathway but did not affect the proteasomal fraction of degradation. Upon inhibition of glucose trimming, the initial lag period was eliminated and degradation thus accelerated. Our results indicated that, although the proteasome is a major player in ERAD, alternative routes are present in mammalian cells and can play an important role in the disposal of both glycoproteins and non-glycoproteins.