p180 promotes the ribosome-independent localization of a subset of mRNA to the endoplasmic reticulum.
p180 promotes the ribosome-independent localization of a subset of mRNA to the endoplasmic reticulum.
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DOI：
10.1371/journal.pbio.1001336
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发表时间：
2012
期刊：
影响因子：
9.8
通讯作者：
Palazzo AF
中科院分区：
文献类型：
--
作者：
Cui XA;Zhang H;Palazzo AF
许多分泌性mRNA定位于内质网不需要核糖体或翻译，而是由p180促进，p180是一种丰富的膜结合蛋白，可能直接与mRNA结合。在后生动物中，大多数编码分泌和膜结合蛋白的mRNA在内质网（ER）表面翻译。尽管这些转录物靶向ER表面可以通过信号序列的翻译来介导，并且它们的维持通过核糖体和易位子之间的相互作用来介导，但越来越清楚的是，存在另外的ER定位途径。在这里，我们证明了许多这些mRNA可以靶向，并保持相关，独立于核糖体和翻译的ER。使用质谱分析与ER结合的多聚核糖体相关的蛋白质，我们确定了可能介导这种替代机制的假定mRNA受体，包括p180，一种丰富的带正电荷的膜结合蛋白。我们证明，p180过表达可以增强与ER的通用mRNA的协会。然后，我们表明，p180包含一个富含赖氨酸的区域，可以直接与RNA在体外相互作用。最后，我们证明，p180是所需的有效的ER锚定散装聚（A）和某些成绩单，如胎盘碱性磷酸酶和钙网蛋白，ER。总之，我们提供了，据我们所知，第一个机制的细节替代途径，以靶向和维持mRNA的ER。很可能这种替代途径不仅增强了蛋白质分选的保真度，而且还将mRNA定位于ER的各个亚结构域，从而有助于细胞组织。编码分泌或膜结合蛋白质的信使RNA（mRNA）必须被递送到内质网（ER）表面，然后维持在内质网表面。这些mRNA编码一个短的多肽，在翻译过程中将mRNA/核糖体/新生蛋白复合物靶向ER表面;然而，最近的研究支持可能存在于mRNA分子本身内的额外ER定位信号的存在。在这里，我们证明了这些mRNA的一部分，其编码的蛋白质是注定要分泌，包含的信息，其目标和锚定他们的ER独立的编码的多肽或其协会的核糖体。我们鉴定了ER上可能作为这些mRNA受体的蛋白质。然后，我们表明，这些候选人的膜结合受体，p180，是必需的某些mRNA的维持在ER的表面上，即使在它们翻译成蛋白质被破坏。我们还证明，p180含有一个区域，直接结合到RNA，并可能介导锚定的mRNA的ER。因此，我们的研究提供了第一个替代途径的机制细节，用于确保分泌型mRNA及其编码的蛋白质在ER中到达其正确的目的地。
The localization of many secretory mRNAs to the endoplasmic reticulum does not require ribosomes or translation, but is instead promoted by p180, an abundant, membrane-bound protein that likely binds directly to mRNA. In metazoans, the majority of mRNAs coding for secreted and membrane-bound proteins are translated on the surface of the endoplasmic reticulum (ER). Although the targeting of these transcripts to the surface of the ER can be mediated by the translation of a signal sequence and their maintenance is mediated by interactions between the ribosome and the translocon, it is becoming increasingly clear that additional ER-localization pathways exist. Here we demonstrate that many of these mRNAs can be targeted to, and remain associated with, the ER independently of ribosomes and translation. Using a mass spectrometry analysis of proteins that associate with ER-bound polysomes, we identified putative mRNA receptors that may mediate this alternative mechanism, including p180, an abundant, positively charged membrane-bound protein. We demonstrate that p180 over-expression can enhance the association of generic mRNAs with the ER. We then show that p180 contains a lysine-rich region that can directly interact with RNA in vitro. Finally, we demonstrate that p180 is required for the efficient ER-anchoring of bulk poly(A) and of certain transcripts, such as placental alkaline phosphatase and calreticulin, to the ER. In summary, we provide, to our knowledge, the first mechanistic details for an alternative pathway to target and maintain mRNA at the ER. It is likely that this alternative pathway not only enhances the fidelity of protein sorting, but also localizes mRNAs to various subdomains of the ER and thus contributes to cellular organization. Messenger RNAs (mRNAs) that encode secreted or membrane-bound proteins must be delivered to, and then maintained on, the surface of the endoplasmic reticulum (ER). These mRNAs encode a short polypeptide that targets the mRNA/ribosome/nascent protein complexes to the ER surface during translation; however, recent studies support the existence of additional ER-localization signals that might be present within the mRNA molecules themselves. Here, we demonstrate that a fraction of these mRNAs, whose encoded proteins are destined for secretion, contain information that targets and anchors them to the ER independently of their encoded polypeptide or their association to ribosomes. We identify proteins on the ER that may serve as receptors for these mRNAs. We then show that one of these candidate membrane-bound receptors, p180, is required for the maintenance of certain mRNAs on the surface of the ER even after their translation into protein is disrupted. We also demonstrate that p180 contains a region that binds directly to RNA and likely mediates the anchoring of mRNA to the ER. Our study thus provides the first mechanistic details of an alternative pathway used to ensure that secretory mRNAs, and their encoded proteins, reach their proper destination in the ER.
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影响因子：
64.5
作者：
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通讯作者：
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影响因子：
4.8
作者：
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DOI：
10.1111/j.1432-1033.1977.tb11256.x
发表时间：
1977-01-01
期刊：
EUROPEAN JOURNAL OF BIOCHEMISTRY
影响因子：
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作者：
FRESNO, M;JIMENEZ, A;VAZQUEZ, D
通讯作者：
VAZQUEZ, D
DOI：
10.1016/j.bbrc.2009.07.106
发表时间：
2009-10-09
影响因子：
3.1
作者：
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通讯作者：
Gupta, Radhey S.