Shortly after transcription is initiated in eukaryotes, a pre-mRNA's 5' end is modified by the addition of a 7-methylguanosine cap, also known as a 5' cap.[1] The 5' capping modification is initiated by the addition of a GTP to the 5' terminal nucleotide of the pre-mRNA in reverse orientation followed by the addition of methyl groups to the G residue.[8] 5' capping is essential for the production of functional mRNAs since the 5' cap is responsible for aligning the mRNA with the ribosome during translation.[8]