Dani H M, Singh J, Singh S
Department of Biochemistry, Panjab University, Chandigarh, India.
J Biol Regul Homeost Agents. 2003 Oct-Dec;17(4):303-7.
The signal recognition particle (SRP) is a unique moiety in living cells, which has been conserved during evolution for protein targeting and translocation across membranes in collaboration with its receptor (SR). The structural and functional features of its components, (six polypeptides and RNA) are being rapidly elucidated. We have endeavored in this review to epitomize most recent advances in this field. Its two domains (S and Alu) play important roles in signal recognition, elongation arrest and protein targeting of the polypeptide being synthesized in the cytoplasm. SRP14 and SRP9 help in the elongation arrest by interacting with signal peptide. GTPase activity of SRP54 releases SRP from SR. In addition, alpha and beta subunits of SR also possess GTPase activities and the three GTPases help in docking of nascent peptide chain-ribosome complex to the translocation site. Further strides in proteomics employing mass spectrometry and X-ray crystallography are expected to throw more light on the molecular events occurring during protein targeting and translocation.
信号识别颗粒（SRP）是活细胞中的一种独特成分，在进化过程中它一直得以保留，以便与它的受体（SR）协作进行蛋白质靶向及跨膜转运。其组分（六种多肽和RNA）的结构和功能特征正在迅速得到阐明。在这篇综述中，我们力图概括该领域的最新进展。它的两个结构域（S和Alu）在信号识别、延伸停滞以及对细胞质中正在合成的多肽进行蛋白质靶向方面发挥着重要作用。SRP14和SRP9通过与信号肽相互作用来帮助延伸停滞。SRP54的GTP酶活性使SRP从SR上释放。此外，SR的α和β亚基也具有GTP酶活性，这三种GTP酶有助于新生肽链-核糖体复合物对接至转运位点。预计蛋白质组学在质谱分析和X射线晶体学方面的进一步进展将更清楚地揭示蛋白质靶向和转运过程中发生的分子事件。
