Figure 1.

Fibrillarin-associated human snoRNAs. (A) Resolution of RNAs isolated from an antifibrillarin precipitate of HeLa cell extract. The 3′ end-labeled RNAs were first fractionated on a standard 15% denaturing polyacrylamide gel. Twenty-three bands were excised, eluted, and further resolved on a 15% gel with a ratio of acrylamide/bis-acrylamide of 9:1. U62 (Upper) and U63 (Lower) snoRNAs are indicated by arrows. Previously identified snoRNAs are indicated by dots. From largest to smallest they are: U16 (27), U14 (28), U45a (11), U45a variant (11), U20 (29), U28 (20), U26 (20), and U45b (11). (B) Sequences of U62 and U63 snoRNAs and their predicted base-pairing interactions with rRNAs. Conserved boxes C, D, and D′ are shown in boldface type. Filled circles indicate 2′-O-methylated residues in rRNA.