Like all cellular proteins, membrane proteins are synthesized by ribosomes. But unlike their soluble counterparts, highly hydrophobic membrane proteins require auxiliary machineries to prevent aggregation in aqueous cellular compartments. The principal machine is the translocon, which works in concert with ribosomes to manage the orderly insertion of alpha-helical membrane proteins directly into the endoplasmic reticulum membrane of eukaryotes or into the plasma membrane of bacteria. In the course of insertion, membrane proteins come into thermodynamic equilibrium with the lipid membrane, where physicochemical interactions determine the final three-dimensional structure. Much progress has been made during the past several years toward understanding the physical chemistry of membrane protein stability, the structure of the translocon machine, and the mechanisms by which the translocon selects and inserts transmembrane helices. We review this progress and consider the connection between the physical principles of membrane protein stability and translocon selection of transmembrane helices.

中文翻译：

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Translocons如何选择跨膜螺旋。

像所有细胞蛋白一样，膜蛋白是由核糖体合成的。但是与它们的可溶对应物不同，高度疏水的膜蛋白需要辅助机制来防止在水性细胞室中聚集。主要机器是translocon，它与核糖体协同工作，以控制α-螺旋膜蛋白直接有序插入真核生物的内质网或细菌的质膜。在插入过程中，膜蛋白与脂质膜达到热力学平衡，其中物理化学相互作用决定了最终的三维结构。在过去几年中，在了解膜蛋白稳定性的物理化学，translocon机器的结构，以及translocon选择和插入跨膜螺旋的机制。我们回顾了这一进展，并考虑了膜蛋白稳定性的物理原理与跨膜螺旋的translocon选择之间的联系。