Figure 6.

Identification of an intronic U99 retrogene. Sequence alignment of a U99 mouse snoRNA retrogene with its functional counterpart. Boundaries of the mature U99 sequence are denoted by vertical arrowheads. Direct repeats flanking the snoRNA retrogene are overlined (arrow), while the poly(A) stretch is underlined and the H and ACA motifs boxed. Bottom: intronic location of the U99 retrogene within the mouse Siat5 gene, with indication of a spliced EST (AK034863) connecting the U99 retrogene-containing intron to the rest of the Siat5 gene. Exons are represented by white boxes, splicing events by dotted lines, and the U99 retrogene by an open arrow (the flanking direct repeats are depicted by arrowheads). Nucleotides conserved between gene and retrogene are indicated by asterisks.