M phase phosphoprotein 10 is a human U3 small nucleolar ribonucleoprotein component.
M phase phosphoprotein 10 is a human U3 small nucleolar ribonucleoprotein component.
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DOI：
10.1091/mbc.9.2.437
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发表时间：
1998-02
影响因子：
3.3
通讯作者：
J. Westendorf;Konstantin N. Konstantinov;S. Wormsley;M. Shu;N. Matsumoto-Taniura;F. Pirollet;F. Klier;L. Gerace;S. Baserga
中科院分区：
文献类型：
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作者：
J. Westendorf;Konstantin N. Konstantinov;S. Wormsley;M. Shu;N. Matsumoto-Taniura;F. Pirollet;F. Klier;L. Gerace;S. Baserga
我们以前开发了一种新的技术用于分离编码M期磷蛋白（MPPs）的cDNA。在本文所述的工作中，我们进一步表征了MPP10，我们确定的10种新蛋白之一，关于其潜在的核仁功能。我们发现，通过细胞分级分离，几乎所有的MPP 10被发现在分离的核仁。通过免疫荧光，MPP 10共定位与核仁纤维蛋白和其他已知的核仁蛋白质在间期细胞，但没有检测到的卷曲体染色的纤维蛋白或p80卷曲蛋白，蛋白质只发现在卷曲体。当用放线菌素D处理核仁时，几乎所有的MPP 10都被发现在纤维帽中，其中含有参与rRNA加工的蛋白质。在细胞周期的早期至中期，MPP 10与原纤维蛋白共定位于染色体表面。在末期，MPP 10被发现在类似于核仁衍生体和核仁前体的细胞结构中。这些机构缺乏原纤蛋白，一个先前描述的组成部分核仁衍生的机构和prenucleolar机构，然而，和大部分的MPP 10到达核仁晚于原纤蛋白。为了进一步检查MPP 10的性质，我们从细胞超声处理物中免疫沉淀它。所得沉淀物含有U3小核仁RNA（snoRNA），但没有显著量的其他盒C/D snoRNA。MPP10与U3 snoRNA的这种结合对400 mM盐是稳定的，并表明MPP10是人U3小核仁核糖核蛋白的组分。
We have previously developed a novel technique for isolation of cDNAs encoding M phase phosphoproteins (MPPs). In the work described herein, we further characterize MPP10, one of 10 novel proteins that we identified, with regard to its potential nucleolar function. We show that by cell fractionation, almost all MPP10 was found in isolated nucleoli. By immunofluorescence, MPP10 colocalized with nucleolar fibrillarin and other known nucleolar proteins in interphase cells but was not detected in the coiled bodies stained for either fibrillarin or p80 coilin, a protein found only in the coiled body. When nucleoli were separated into fibrillar and granular domains by treatment with actinomycin D, almost all the MPP10 was found in the fibrillar caps, which contain proteins involved in rRNA processing. In early to middle M phase of the cell cycle, MPP10 colocalized with fibrillarin to chromosome surfaces. At telophase, MPP10 was found in cellular structures that resembled nucleolus-derived bodies and prenucleolar bodies. Some of these bodies lacked fibrillarin, a previously described component of nucleolus-derived bodies and prenucleolar bodies, however, and the bulk of MPP10 arrived at the nucleolus later than fibrillarin. To further examine the properties of MPP10, we immunoprecipitated it from cell sonicates. The resulting precipitates contained U3 small nucleolar RNA (snoRNA) but no significant amounts of other box C/D snoRNAs. This association of MPP10 with U3 snoRNA was stable to 400 mM salt and suggested that MPP10 is a component of the human U3 small nucleolar ribonucleoprotein.