Elongation arrest is not a prerequisite for secretory protein translocation across the microsomal membrane.
Elongation arrest is not a prerequisite for secretory protein translocation across the microsomal membrane.
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DOI：
10.1083/jcb.100.6.1913
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发表时间：
1985-06
期刊：
影响因子：
--
通讯作者：
Walter P
中科院分区：
文献类型：
--
作者：
Siegel V;Walter P
信号识别颗粒（SRP）是一种核糖核蛋白，由6种不同的多肽和1个胞质小分子7SL RNA组成。以前的研究表明，通过(a)在特定点阻止分泌前新生链的伸长，以及(b)与SRP受体相互作用，促进分泌蛋白在内质网的共翻译易位，SRP受体是内质网的一种完整的膜蛋白，在释放伸长阻滞中是活跃的。最近设计了一种程序，通过该程序可以将颗粒分解成蛋白质和RNA成分。我们进一步将SRP蛋白分离成四个均匀的部分。当它们相互重组并与7SL RNA重组时，它们形成了完全活性的SRP。缺少特定蛋白质的颗粒被组装起来，希望其中一些能够保留一些功能活性。缺乏9-kD和14- kD多肽的SRP（-9/14）在促进易位方面完全活跃，但在阻止延伸方面完全不活跃。这意味着，延长阻滞不是蛋白质易位的先决条件。SRP受体是SRP（-9/14）介导的易位发生所必需的，因此除了释放延伸阻滞外，它还必须在易位过程中发挥一定的作用。
Signal recognition particle (SRP) is a ribonucleoprotein consisting of six distinct polypeptides and one molecule of small cytoplasmic 7SL RNA. It was previously shown to promote the co-translational translocation of secretory proteins across the endoplasmic reticulum by (a) arresting the elongation of the presecretory nascent chain at a specific point, and (b) interacting with the SRP receptor, an integral membrane protein of the endoplasmic reticulum which is active in releasing the elongation arrest. Recently a procedure was designed by which the particle could be disassembled into its protein and RNA components. We have further separated the SRP proteins into four homogeneous fractions. When recombined with each other and with 7SL RNA, they formed fully active SRP. Particles missing specific proteins were assembled in the hope that some of these would retain some functional activity. SRP(-9/14), the particle lacking the 9-kD and 14- kD polypeptides, was fully active in promoting translocation, but was completely inactive in elongation arrest. This implied that elongation arrest is not a prerequisite for protein translocation. SRP receptor was required for SRP(-9/14)-mediated translocation to occur, and thus must play some role in the translocation process in addition to releasing the elongation arrest.