The affinity of signal recognition particle for presecretory proteins is dependent on nascent chain length.
The affinity of signal recognition particle for presecretory proteins is dependent on nascent chain length.
复制标题
信号识别颗粒对分泌前蛋白的亲和力取决于新生链的长度。
DOI：
10.1002/j.1460-2075.1988.tb03007.x
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发表时间：
1988
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
我们已经开发了一种不同长度的不完全催乳素前链以不依赖于伸长的方式靶向内质网(ER)膜的方法。该反应具有与新生链跨ER膜转位相同的分子要求，即它是信号识别粒子(SRP)依赖的，要求新生链以肽tRNA的形式存在(即最有可能与核糖体相关)，并将其信号序列暴露在核糖体之外。我们发现，当链的长度超过140个氨基酸时，靶向反应的效率急剧下降，这可能反映了新生的链-核糖体复合体对SRP的亲和力降低。因此，在生理SRP浓度(10 NM)时，这些链的靶向能力出现了一个急剧的截止点，而当SRP浓度较高(270 NM)时，所有链都可以成为靶向。在动力学实验中，发现高浓度的SRP改变了伸长时间，在此之后，新生多肽不再发生移位。
We have developed an assay in which incomplete preprolactin chains of varying lengths are targeted to the endoplasmic reticulum (ER) membrane in an elongation independent manner. The reaction had the same molecular requirements as nascent chain translocation across the ER membrane, namely, it was signal recognition particle (SRP) dependent, and required the nascent chain to be present as peptidyl tRNA (i.e. most likely ribosome associated) and to have its signal sequence exposed outside the ribosome. We found that the efficiency of the targeting reaction dropped dramatically as the chains grew longer than 140 amino acids in length, which probably reflected a decrease in affinity of the nascent chain‐ribosome complex for SRP. Thus at physiological SRP concentrations (10 nM) there appears a sharp cut‐off point in the ability of these chains to be targeted, while at high SRP concentrations (270 nM) all chains could be targeted. In kinetic experiments, high concentrations of SRP were found to change the time in elongation after which translocation of the nascent polypeptide could no longer occur.