In which post-transcriptional modification, an unusual nucleotide 7-methyl guanosine triphosphate (7-mGTP) is added to the 5’ end of m RNA of eukaryotes?

During transcription of eukaryotic mRNA, the primary transcript formed is called hnRNA (heterogenous nuclear RNA). It is inactive and subjected to processing. In the initial step of processing, at the time of progress of transcription an unusual nucleotide 7-methyl Guanosine triphosphate is added at the 5^! end of transcript in template independent manner by Guanosyl transferase and the process is called capping. Later tailing and splicing are done to form active mRNA that can be transported to cytoplasm to take part in translation.