Figure 6.

Revised secondary structure model of the Euglena U3 snoRNA. In this proposed model, the 5'-trimethylguanosine cap (5'-TMG cap) is indicated in orange, the phylogenetically conserved and functionally essential box GAC, A', A, C', B, C, and D elements are shown in blue. Pseudouridine (Ψ) residues are indicated in green. Nucleotide heterogeneities identified in the Euglena U3 snoRNA gene variants are denoted by the red circles. Nucleotides forming a K-turn motif are highlighted on a gray background. Conventional Watson-Crick base-pairing interactions are depicted as dashes (-) and G/U pairings are identified by dots (•). An alignment of known U3 snoRNA sequences from representative organisms is shown in Additional file 1.