Figure 2. The pathway and fates of modified mRNAs.

Shown are the steps an mRNA may undergo following transcription and splicing. Starting with addition of the non-templated triphosphorylated G (red), followed by sequential methylation of the cap starting with m⁷G (green), followed by ribose and base methylation of the first two template nucleotides. mRNAs may also undergo internal modifications such as m⁶A or inosine (not shown). Asterisks (*) denote less common modifications such as 5-methylcytosine (m⁵C), pseudouridine, N1-methyladenosine (m¹A), ribose methylation, acetylation, etc. CAP formation is important for nuclear export. The mRNA can also be demethylated in the nucleus by the demetylase FTO and ALKBH5. The fate of mRNAs in the cytoplasm can be determined by their interaction with modification-specific mRNA-biding proteins such as YTHDF1/2/3 or IGFBPs.