Wolin S L, Walter P
Department of Biochemistry and Biophysics, University of California Medical School, San Francisco 94143-0448.
J Cell Biol. 1989 Dec;109(6 Pt 1):2617-22. doi: 10.1083/jcb.109.6.2617.
Signal recognition particle (SRP) is a ribonucleoprotein that functions in the targeting of ribosomes synthesizing presecretory proteins to the ER. SRP binds to the signal sequence as it emerges from the ribosome, and in wheat germ extracts, arrests further elongation. The translation arrest is released when SRP interacts with its receptor on the ER membrane. We show that the delay of elongation mediated by SRP is not unique to wheat germ translation extracts. Addition of mammalian SRP to reticulocyte lysates resulted in a delay of preprolactin synthesis due to increased ribosome pausing at specific sites on preprolactin mRNA. Addition of canine pancreatic microsomal membranes to reticulocyte lysates resulted in an acceleration of preprolactin synthesis, suggesting that the endogenous SRP present in the reticulocyte lysate also delays synthesis of secretory proteins.
信号识别颗粒（SRP）是一种核糖核蛋白，其功能是将合成分泌前体蛋白的核糖体靶向内质网。当信号序列从核糖体中出现时，SRP会与之结合，在小麦胚芽提取物中，它会阻止进一步的延伸。当SRP与内质网膜上的受体相互作用时，翻译停滞就会解除。我们发现，由SRP介导的延伸延迟并非小麦胚芽翻译提取物所特有。将哺乳动物SRP添加到网织红细胞裂解物中会导致前催乳素合成延迟，这是由于核糖体在催乳素原mRNA的特定位点上停顿增加所致。将犬胰腺微粒体膜添加到网织红细胞裂解物中会导致前催乳素合成加速，这表明网织红细胞裂解物中存在的内源性SRP也会延迟分泌蛋白的合成。
