CPuORF correlates with miRNA responsive elements on protein evolutionary rates

miRNA is increasingly being recognized as a key regulator of metabolism in animals. A wealth of evidence has suggested that miRNA mainly binds 3′ UTR of mRNA and modulates the cell activities via repressing the mRNA translation. However, as the translation initiates at 5′ UTR, cis elements like upstream open reading frame (uORF) resided in 5′ UTR may also affect the translation efficiency or elongation. In this study, we performed a systematic analysis of miRNA responsive elements (MREs) and uORF of the same transcript in three model organisms (human, mouse, and Drosophila). Intriguingly, we found that the 3′ UTR length grew with the complexity of species (human > mouse > Drosophila), in sharp contrast with the invariability of 5′ UTR. Additionally, MRE number correlated well with the 3′ UTR length, while uORF number showed a weak correlation with the 5′ UTR length. Further, we found that human genes with conserved peptide upstream open reading frame (CPuORF) tend to have more MREs and lower evolutionary rates, which provides new insights into the correlation between UTR properties and translational control in animals.