Halic Mario, Beckmann Roland
Institut für Biochemie, Charité, Universitätsmedizin Berlin, Monbijoustrasse 2, D-10117 Berlin, Germany.
Curr Opin Struct Biol. 2005 Feb;15(1):116-25. doi: 10.1016/j.sbi.2005.01.013.
The synthesis of secretory or integral membrane proteins can be directly coupled to their translocation across or insertion into membranes. In co-translational targeting, the translation machine, the ribosome, is transferred to the respective membrane by the signal recognition particle (SRP) and its receptor (SR) as soon as a signal sequence emerges. Protein synthesis can continue at the membrane, with the nascent peptide chain directly inserting into the ribosome-bound protein-conducting channel, the Sec61 complex. During the past two years, several structures have been solved by crystallography and cryo-electron microscopy that represent distinct functional states of the SRP cycle. On this basis, the first structure-based models can be suggested that explain important aspects of protein targeting, such as the SRP-ribosome and SRP-SR interactions.
分泌性或整合膜蛋白的合成可直接与其跨膜转运或插入膜内的过程相偶联。在共翻译靶向中，一旦信号序列出现，翻译机器即核糖体就会被信号识别颗粒（SRP）及其受体（SR）转移至相应的膜上。蛋白质合成可在膜上继续进行，新生肽链直接插入与核糖体结合的蛋白质传导通道即Sec61复合体中。在过去两年里，通过晶体学和冷冻电子显微镜解析出了几种代表SRP循环不同功能状态的结构。在此基础上，可以提出首个基于结构的模型，用以解释蛋白质靶向的重要方面，比如SRP-核糖体和SRP-SR相互作用。
