The Mammalian Cytosolic Thioredoxin Reductase Pathway Acts via a Membrane Protein to Reduce ER-localised Proteins
The Mammalian Cytosolic Thioredoxin Reductase Pathway Acts via a Membrane Protein to Reduce ER-localised Proteins
复制标题
哺乳动物细胞质硫氧还蛋白还原酶途径通过膜蛋白减少内质网定位蛋白
DOI：
10.1101/830026
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Cao X
中科院分区：
文献类型：
--
作者：
Cao X
折叠进入哺乳动物分泌途径的蛋白质需要插入正确的二硫化物。二硫化物的形成既包括其插入的氧化途径，也包括去除不正确形成的二硫化物的还原途径。这些二硫化物的还原对于正确折叠和错误折叠蛋白质的降解至关重要。在此之前，我们证明了还原途径是由细胞质中产生的NADPH驱动的。在这里，通过使用纯化的蛋白质和内质网微粒体膜重构通路，我们证明硫氧还蛋白还原酶系统提供了内质网管内还原蛋白质所需的最小胞质成分。特别是，该通路的饱和及其蛋白酶敏感性表明，膜蛋白需要将电子从细胞质溶胶输送到内质网。这些结果为细胞质溶胶在调节内质网氧化还原稳态、确保正确的蛋白质折叠和促进错误折叠的内质网蛋白降解方面的关键作用提供了令人信服的证据。
Folding of proteins entering the mammalian secretory pathway requires the insertion of the correct disulfides. Disulfide formation involves both an oxidative pathway for their insertion and a reductive pathway to remove incorrectly formed disulfides. Reduction of these disulfides is crucial for correct folding and degradation of misfolded proteins. Previously, we showed that the reductive pathway is driven by NADPH generated in the cytosol. Here, by reconstituting the pathway using purified proteins and ER microsomal membranes, we demonstrate that the thioredoxin reductase system provides the minimal cytosolic components required for reducing proteins within the ER lumen. In particular, saturation of the pathway and its protease sensitivity demonstrates the requirement for a membrane protein to shuttle electrons from the cytosol to the ER. These results provide compelling evidence for the crucial role of the cytosol in regulating ER redox homeostasis, ensuring correct protein folding and facilitating the degradation of misfolded ER proteins.