The structures of pseudouridine (Ψ), 1-methylpseudouridine (m1Ψ), 1-methyl-3-(3-amino-3-carboxypropyl)pseudouridine (m1acp3Ψ), 2′-O-methylpseudouridine (Ψm), 1-methyl-3-(4-hydroxybutyl)pseudouridine (m1hb3Ψ), 3-(3-amino-3-carboxypropyl)uridine (acp3U), 3-(4-amino-4-carboxybutyl)uridine (acb3U), 3-(4-hydroxybutyl)uridine (hb3U), and 3-(3-carboxybutyl)uridine (cp3U) are shown.