Whole proteome pI values correlate with subcellular localizations of proteins for organisms within the three domains of life.
Whole proteome pI values correlate with subcellular localizations of proteins for organisms within the three domains of life.
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DOI：
10.1101/gr.158701
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发表时间：
2001-04
期刊：
影响因子：
7
通讯作者：
R. Schwartz;Claire Ting;J. King
中科院分区：
文献类型：
--
作者：
R. Schwartz;Claire Ting;J. King
等电点（pI）值长期以来一直是区分蛋白质的标准量度。本文分析了在选择的完全测序的基因组的所有预测的ORF的计算估计的pI值的分布。pI值的直方图证实了先前在细菌和古细菌基因组中观察到的双峰性（），并揭示了真核生物基因组中的三峰性。一个类似的分析子集的非冗余的蛋白质序列数据库产生的完整的数据库，通过选择亚细胞定位显示，序列注释为对应于胞质和完整的膜蛋白的pI分布，似乎对应于两个观察到的模式的细菌和古细菌。此外，核蛋白具有更广泛的分布，这可能解释了在真核生物中观察到的第三种模式。在此基础上的pI和亚细胞定位之间的关联，我们得出结论，双峰字符的整个蛋白质组的pI值在细菌和古细菌和真核生物中的三峰字符可能是蛋白质组的一般属性，并与需要不同的pI值取决于亚细胞定位。我们的分析还表明，膜相关蛋白组成的蛋白质组的比例目前可能被低估。
Isoelectric point (pI) values have long been a standard measure for distinguishing between proteins. This article analyzes distributions of pI values estimated computationally for all predicted ORFs in a selection of fully sequenced genomes. Histograms of pI values confirm the bimodality that has been observed previously for bacterial and archaeal genomes () and reveal a trimodality in eukaryotic genomes. A similar analysis on subsets of a nonredundant protein sequence database generated from the full database by selecting on subcellular localization shows that sequences annotated as corresponding to cytosolic and integral membrane proteins have pI distributions that appear to correspond with the two observed modes of bacteria and archaea. Furthermore, nuclear proteins have a broader distribution that may account for the third mode observed in eukaryotes. On the basis of this association between pI and subcellular localization, we conclude that the bimodal character of whole proteome pI values in bacteria and archaea and the trimodal character in eukaryotes are likely to be general properties of proteomes and are associated with the need for different pI values depending on subcellular localization. Our analyses also suggest that the proportions of proteomes consisting of membrane-associated proteins may be currently underestimated.