Homo sapiens E3 snoRNA.
This H/ACA box snoRNA was cloned by Ruff et al. (1993). It was shown by Rimoldi et al. (1993) that E3 can be cross-linked by psoralen to the 18S rRNA region (between residues 1021 and 1639) of the nucleolar pre-rRNA. E3 RNA degradation of frog oocytes shuts down production of 32S pre-rRNA from 36S pre-rRNA, suggesting that E3 snoRNA is involved in rRNA processing at or near the 5' end of 5.8S RNA (site 3) (Mishra and Eliceiri, 1997). Ganot et al. (1997b) recognised its hairpin-hinge-hairpin-tail structure characteristic of H/ACA box snRNAs. The role of E3 in guiding the pseudouridylation of U4390 in 28S rRNA was evidenced by Ganot et al. (1997a). The pseudouridylation of this residue was previously reported by Ofengand and Bakin (1997). The H/ACA box snoRNAs E3,HBI-61 and ACA4, and the C/D box snoRNA snR39B share the same host gene (EIF4A2).