Figure 1.

Overview map of U3 snoRNAs. The schematic overview on the left (redrawn from Marz and Stadler [3]) defines the nomenclature of the 10 stem and hairpin regions, and indicates the location of the conserved box motifs. The detail on the right, summarizes the particular features of fungal U3 snoRNAs, including the more complex structure of M1. It also indicates the insertion points of introns, which are predominantly located within the 5’ arm of the stem-loop structure M1. The lengths of the bars and the corresponding numbers give the number of species with introns at a particular location, the color indicates their membership in one of the major clade. The drawing was constructed using R2R [14].