7-Methyl-guanosine and efficiency of RNA translation

Brome mosaic virus RNAs 3 and 4 were chemically modified to remove the terminal 7-methyl-guanosine (m7G) structure, and the modified RNAs were tested for their messenger activity in a cell-free system derived from wheat embryo. Amino acid incorporation and ribosome-binding data show that removal of m7G results in reduction, but not complete abolition, of the messenger activity of the RNA. This suggests that the function of m7G may be related to efficient translation of messenger RNA. Possible involvement of other structural factors in RNA translation is discussed.