Reuter Max, Engelstädter Jan, Fontanillas Pierre, Hurst Laurence D
Mol Biol Evol. 2008 May;25(5):801-4. doi: 10.1093/molbev/msn044. Epub 2008 Feb 21.
Eukaryotic mRNAs are headed by a stretch of noncoding sequence, the 5' untranslated region (UTR). It has been proposed that the length of 5' UTRs is selectively neutral and evolves under a process of stochastic destruction and recruitment of core promoter elements, combined with selection against the premature initiation of translation. We test this null model by investigating whether 5' UTR length varies with genomic GC content, an implicit prediction of the model. Using simulations, we show that the null model predicts a positive relationship between GC content and UTR length for genes regulated by a TATA box. Although this prediction is borne out qualitatively in genomic data from yeast, fruit flies, and humans, we find marked quantitative discrepancies. We conclude that UTR length may be shaped to some degree by the forces considered in the null model but that the model fails to provide a complete explanation for UTR length evolution.
真核生物的信使核糖核酸（mRNA）头部有一段非编码序列，即5'非翻译区（UTR）。有人提出，5'UTR的长度是选择性中性的，并且在核心启动子元件的随机破坏和招募过程中进化，同时伴随着对翻译过早起始的选择。我们通过研究5'UTR长度是否随基因组GC含量变化来检验这个零模型，这是该模型的一个隐含预测。通过模拟，我们表明零模型预测对于由TATA框调控的基因，GC含量与UTR长度之间存在正相关关系。尽管这一预测在酵母、果蝇和人类的基因组数据中得到了定性验证，但我们发现了明显的定量差异。我们得出结论，UTR长度可能在一定程度上受到零模型中所考虑的力量的影响，但该模型未能为UTR长度的进化提供完整的解释。
