Dependence of translation on 5'-terminal methylation of mRNA.

Many eukaryotic cell and viral mRNAs contain 5'-terminal m7G(5')ppp(5')N. Methylation is important for the in vitro translation of vesicular stomatitis virus and reovirus mRNAs. Unmethylated viral mRNAs are methylated by cell-free extrascts of wheat germ and L cells to form 5'-terminal structures of the type, m7GpppN and m7GpppNm, respectively. Rabbit globin mRNA also contains 5'-terminal 7-methylguanosine (m7G). Removal of the m7G by beta-elimination decreases translation. The efficient binding of mRNA to ribosomes is dependent on the presence of 5'-terminal m7G.