Proteomic characterization of evolutionarily conserved and variable proteins of arabidopsis cytosolic ribosomes
Proteomic characterization of evolutionarily conserved and variable proteins of arabidopsis cytosolic ribosomes
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DOI：
10.1104/pp.104.053637
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发表时间：
2005-03-01
期刊：
影响因子：
7.4
通讯作者：
Bailey-Serres, J
中科院分区：
文献类型：
--
作者：
Chang, IF;Szick-Miranda, K;Bailey-Serres, J
拟南芥80 S核糖体的分析利用高速离心、蔗糖梯度分离、一维和二维凝胶电泳、液相色谱纯化和质谱分析，（基质辅助激光解吸/电离飞行时间和电喷雾电离）鉴定了74种核糖体蛋白（r-蛋白），其中73个是大鼠r-蛋白的直系同源物，一个是植物特异性r-蛋白P3。30个小亚基（40 S）和44个大亚基（60 S）的r-蛋白被确认。此外，哺乳动物活化蛋白激酶C受体的直系同源物，一种天冬氨酸-天冬氨酸结构域重复蛋白，被发现与40 S亚基和多聚核糖体相关。基于每个r-蛋白以单拷贝存在的预测，拟南芥80 S核糖体的质量估计为3.2 MD（1，159 kD 40 S; 2，010 kD 60 S），其中4个单拷贝rRNA（18 S，26 S，5.8S和5S）占质量的53%。尽管在真核生物中的r-蛋白组成的进化保守性很强，但拟南芥80 S核糖体的组成是可变的，这是由于约25%的r-蛋白的质量或电荷的差异。这是r蛋白基因家族内氨基酸序列差异和单个r蛋白的翻译后修饰（例如氨基末端乙酰化、磷酸化）的结果。例如，由于r蛋白基因的进化分歧，不同类型的r蛋白S15 a和P2积累在核糖体中。核糖体的变化也是由于氨基酸序列的分歧和差异磷酸化的r-蛋白S6的羧基末端。核糖体异质性的差异mRNA翻译的作用进行了讨论。
Analysis of 80S ribosomes of Arabidopsis (Arabidopsis thaliana) by use of high-speed centrifugation, sucrose gradient fractionation, one- and two-dimensional gel electrophoresis, liquid chromatography purification, and mass spectrometry (matrix-assisted laser desorption/ionization time-of-flight and electrospray ionization) identified 74 ribosomal proteins (r-proteins), of which 73 are orthologs of rat r-proteins and one is the plant-specific r-protein P3. Thirty small (40S) subunit and 44 large (60S) subunit r-proteins were confirmed. In addition, an ortholog of the mammalian receptor for activated protein kinase C, a tryptophan-aspartic acid-domain repeat protein, was found to be associated with the 40S subunit and polysomes. Based on the prediction that each r-protein is present in a single copy, the mass of the Arabidopsis 80S ribosome was estimated as 3.2 MD (1,159 kD 40S; 2,010 kD 60S), with the 4 single-copy rRNAs (18S, 26S, 5.8S, and 5S) contributing 53% of the mass. Despite strong evolutionary conservation in r-protein composition among eukaryotes, Arabidopsis 80S ribosomes are variable in composition due to distinctions in mass or charge of approximately 25% of the r-proteins. This is a consequence of amino acid sequence divergence within r-protein gene families and posttranslational modification of individual r-proteins (e.g. amino-terminal acetylation, phosphorylation). For example, distinct types of r-proteins S15a and P2 accumulate in ribosomes due to evolutionarily divergence of r-protein genes. Ribosome variation is also due to amino acid sequence divergence and differential phosphorylation of the carboxy terminus of r-protein S6. The role of ribosome heterogeneity in differential mRNA translation is discussed.