Protein phosphorylation is a critical post-translational modification in all aspects of plant biology. The position of the phosphorylated site is an essential characteristic of phosphoproteins. The distribution of phosphosites is associated with both protein sequences and functions. Proteomics and multivariate data analysis were performed on phosphorylated proteins to investigate the relationship between phosphosites and protein attributes in potato tubers. A total of 488 phosphoproteins were identified. In total, 1028 of serine and threonine phosphorylation sites contained 676 phosphorylation sites outside of the predicted homology domain. All phosphoproteins shared 7 common phosphorylation motifs ([SP], [RxxSP], [GSP], [SSP], [RxxS], [SDxE], and [TP]). These motifs participated in a variety of metabolic processes. Phosphorylated proteins were classified into some important pathways by GO and KEGG enrichment analysis, including glucose metabolism, mRNA production, and the MAPK pathway. OPLS models were employed to identify a correlation between the phosphosites and various protein attributes. Phosphorylation sites of transcription and translation protein were located at 13% and 98% positions in the proteins, respectively. The position was a vital region of signal transduction protein at 89% in the phosphoprotein. Moreover, the C-terminal region was closely correlated with phosphoproteins of protein biogenesis and storage. These results suggest that the frequency distribution of phosphosites remained stable along the sequences of proteins. The phosphorylation of serine/threonine residues occurs readily in disordered regions at N- and C-termini of proteins. N- and C-termini of proteins represent a possible vital region of phosphorylation for the three types of protein functions in potato tubers.

中文翻译：

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马铃薯块茎的磷酸化蛋白质组学分析揭示了磷酸化位点占有率与蛋白质属性之间可能存在的相关性

蛋白质磷酸化是植物生物学各个方面的关键翻译后修饰。磷酸化位点的位置是磷蛋白的基本特征。磷酸位点的分布与蛋白质序列和功能有关。对磷酸化蛋白质进行蛋白质组学和多变量数据分析，以研究马铃薯块茎中磷位点与蛋白质属性之间的关系。共鉴定出 488 种磷蛋白。总共有 1028 个丝氨酸和苏氨酸磷酸化位点包含 676 个位于预测同源域之外的磷酸化位点。所有磷蛋白都有 7 个常见的磷酸化基序（[SP]、[RxxSP]、[GSP]、[SSP]、[RxxS]、[SDxE] 和 [TP]）。这些基序参与了多种代谢过程。通过 GO 和 KEGG 富集分析，磷酸化蛋白被分类为一些重要的通路，包括葡萄糖代谢、mRNA 产生和 MAPK 通路。采用 OPLS 模型来确定磷位点和各种蛋白质属性之间的相关性。转录和翻译蛋白的磷酸化位点分别位于蛋白质的 13% 和 98% 位置。该位置是磷蛋白中89%的信号转导蛋白的重要区域。此外，C 端区域与蛋白质生物发生和储存的磷蛋白密切相关。这些结果表明磷酸位点的频率分布沿着蛋白质序列保持稳定。丝氨酸/苏氨酸残基的磷酸化很容易发生在蛋白质 N 和 C 末端的无序区域。