7-methylguanosine

The 7-methylguanosine (m⁷G) is a modified nucleoside commonly found in eukaryotes. The m⁷G modification present on the 5'-end of mRNA and on some ncRNA synthesized by RNA polymerase II is called m⁷G cap. It plays a role in transcription, splicing, polyadenylation, nuclear export, stabilization, and translation. In addition, other m⁷G modifications are also found in the tRNA or rRNA. The m⁷G₄₆ modification occurs in bacterial and eukaryotic tRNAs. The m⁷G₁₅₇₅ modification in the 18S rRNA is evolutionarily conserved in eukaryotes.