Spanggord Richard J, Siu Fai, Ke Ailong, Doudna Jennifer A
Department of Molecular and Cell Biology, University of California, Berkeley, California 94705, USA.
Nat Struct Mol Biol. 2005 Dec;12(12):1116-22. doi: 10.1038/nsmb1025. Epub 2005 Nov 20.
The signal recognition particle (SRP) targets nascent proteins to cellular membranes for insertion or secretion by recognizing polypeptides containing an N-terminal signal sequence as they emerge from the ribosome. GTP-dependent binding of SRP to its receptor protein leads to controlled release of the nascent chain into a membrane-spanning translocon pore. Here we show that the association of the SRP with its receptor triggers a marked conformational change in the complex, localizing the SRP RNA and the adjacent signal peptide-binding site at the SRP-receptor heterodimer interface. The orientation of the RNA suggests how peptide binding and GTP hydrolysis can be coupled through direct structural contact during cycles of SRP-directed protein translocation.
信号识别颗粒（SRP）通过识别从核糖体中出现的含有N端信号序列的多肽，将新生蛋白质靶向细胞膜进行插入或分泌。SRP与其受体蛋白的GTP依赖性结合导致新生链被控制释放到跨膜转运体孔中。我们在此表明，SRP与其受体的结合会触发复合物中显著的构象变化，将SRP RNA和相邻的信号肽结合位点定位在SRP-受体异二聚体界面处。RNA的取向表明了在SRP指导的蛋白质转运循环中，肽结合和GTP水解如何通过直接的结构接触相互偶联。
