Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA.
Department of Urology, Boston Children's Hospital, and Department of Surgery and Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA; Central Laboratory of Medical Research Centre, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, Anhui 230001, People's Republic of China.
Cell Rep. 2019 Sep 3;28(10):2517-2526.e5. doi: 10.1016/j.celrep.2019.08.006.
The endoplasmic reticulum (ER) membrane protein complex (EMC) is a key contributor to biogenesis and membrane integration of transmembrane proteins, but our understanding of its mechanisms and the range of EMC-dependent proteins remains incomplete. Here, we carried out an unbiased mass spectrometry (MS)-based quantitative proteomic analysis comparing membrane proteins in EMC-deficient cells to wild-type (WT) cells and identified 36 EMC-dependent membrane proteins and 171 EMC-independent membrane proteins. Of these, six EMC-dependent and six EMC-independent proteins were further independently validated. We found that a common feature among EMC-dependent proteins is that they contain transmembrane domains (TMDs) with polar and/or charged residues. Mutagenesis studies demonstrate that EMC dependency can be converted in cells by removing or introducing polar and/or charged residues within TMDs. Our studies expand the list of validated EMC-dependent and EMC-independent proteins and suggest that the EMC is involved in handling TMDs with residues challenging for membrane integration.
内质网（ER）膜蛋白复合物（EMC）是跨膜蛋白生物发生和膜整合的关键贡献者，但我们对其机制和依赖 EMC 的蛋白质范围的理解仍不完整。在这里，我们进行了一项基于无偏质谱（MS）的定量蛋白质组学分析，比较了 EMC 缺陷细胞与野生型（WT）细胞中的膜蛋白，并鉴定出 36 种依赖 EMC 的膜蛋白和 171 种不依赖 EMC 的膜蛋白。其中，有六个依赖 EMC 和六个不依赖 EMC 的蛋白进一步独立验证。我们发现，依赖 EMC 的蛋白的一个共同特征是它们含有具有极性和/或带电残基的跨膜结构域（TMD）。突变研究表明，通过在 TMD 中去除或引入极性和/或带电残基，可以在细胞中改变 EMC 的依赖性。我们的研究扩展了已验证的依赖 EMC 和不依赖 EMC 的蛋白列表，并表明 EMC 参与处理对膜整合具有挑战性的 TMD 残基。
