Fig. 2
Locations of chemical modifications in mRNA. Chemical RNA modifications are shown in mRNA with their approximate distribution in transcripts. m6A with a widespread distribution prefers to be located in the consensus motif in the 3’UTRs as well as the 5’UTRs, which closely correlate with translation. Although m1A-containing mRNA is 10 times less common than m6A-containing mRNA, m1A is discovered in every segment of mRNA, including the 5’UTRs, CDS and 3’UTRs and mostly in highly structured 5’UTRs. Analogous to m1A, m5C can occur in coding and non-coding regions of mRNA, especially in GC-rich regions. Nevertheless, m5C within different positions regulates transcription differently. Tet-family enzymes prefer to oxidize m5C modifications in coding regions, so hm5C has a greater possibility of being present in CDS. Subsequently, Ψ is demonstrated to have a diversified location, whereas I is present at a large number of sites in the CDS, and U accumulates in 3’UTRs. 2’-O-Me focuses on decorating specific regions of mRNA that encode given amino acids. Additionally, as reversible modifications, most have their own readers, writers and erasers