Modified nucleosides and bizarre 5'-termini in mouse myeloma mRNA

Messenger RNAs from mouse myeloma cells contain N6-methyl adenosine and novel 5' termini having 7-methylguanosine in a 5', 5'triphosphate linkage with ribose-methylated nucleosides. Ten common 5'-terminal sequences of the forms m⁷G^5'ppp^5'NmpNp and m⁷G^5'ppp^5'NmpNmpNp are reported. Structures like this may be a general feature of mRN A in eukaryotes.