RNMT is a widely expressed nuclear protein which is a member of the mRNA cap methyltransferase family. Cap-dependent mRNA translation requires the methylation of the mRNA guanosine cap by RNMT. RNMT catalyzes the transfer of a methyl group from AdoMet（S-adenosylmethionine) to the GpppN end of the growing mRNA at the N-7 position， thus producing AdoHyc（S-adenosylhomocysteine) and m7GpppN terminated RNA.
