Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA.
Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Ave., Pasadena, CA 91125, USA; Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA 91125, USA.
Mol Cell. 2024 Sep 5;84(17):3302-3319.e11. doi: 10.1016/j.molcel.2024.08.005. Epub 2024 Aug 21.
Mammalian membrane proteins perform essential physiologic functions that rely on their accurate insertion and folding at the endoplasmic reticulum (ER). Using forward and arrayed genetic screens, we systematically studied the biogenesis of a panel of membrane proteins, including several G-protein-coupled receptors (GPCRs). We observed a central role for the insertase, the ER membrane protein complex (EMC), and developed a dual-guide approach to identify genetic modifiers of the EMC. We found that the back of Sec61 (BOS) complex, a component of the multipass translocon, was a physical and genetic interactor of the EMC. Functional and structural analysis of the EMC⋅BOS holocomplex showed that characteristics of a GPCR's soluble domain determine its biogenesis pathway. In contrast to prevailing models, no single insertase handles all substrates. We instead propose a unifying model for coordination between the EMC, the multipass translocon, and Sec61 for the biogenesis of diverse membrane proteins in human cells.
哺乳动物膜蛋白执行着重要的生理功能，这些功能依赖于它们在内质网（ER）中的准确插入和折叠。我们使用正向和排列的遗传筛选，系统地研究了一组膜蛋白的生物发生，包括几种 G 蛋白偶联受体（GPCR）。我们观察到插入酶、内质网膜蛋白复合物（EMC）的核心作用，并开发了一种双引导方法来识别 EMC 的遗传修饰物。我们发现，多通道转位通道的组成部分 Sec61 的背面（BOS）复合物是 EMC 的物理和遗传相互作用者。对 EMC⋅BOS 完整复合物的功能和结构分析表明，GPCR 可溶性结构域的特征决定了其生物发生途径。与流行的模型相反，没有一种插入酶可以处理所有的底物。相反，我们提出了一个统一的模型，用于 EMC、多通道转位通道和 Sec61 之间的协调，以在人类细胞中产生各种膜蛋白。
