Schematic of complex modifications. All modifications are shown as nucleosides. (Top left) The mcm5s2U34 modification. The schematic is shown with the 2-thio moiety s2 boxed in green, the 5-carboxymethyl moiety cm5 boxed in red, and the terminal methyl group colored blue. In ncm5U, the terminal methyl group would be an amino group, and the sulfur in the 2-thio moiety would be an oxygen. (Top right) The yW37 modification. The schematic is shown with the methyl/methylene residues added to m1G to form the additional ring of imG14 boxed in green, the α-amino-α-carboxypropyl group added from S-adenosylmethionine boxed in red, and other added groups colored blue. (Bottom left) The t6A37 modification. The schematic is shown with the threonylcarbamoyl group boxed in red. (Bottom right) The Q34 modification.
