Homo sapiens U66 snoRNA. This H/ACA box RNA was cloned from HeLa cells by Ganot et al. (1997b). Its role in guiding pseudouridylation of U119 in 18S rRNA was evidenced by Ganot et al. (1997a). The pseudouridylation of this residue was previously reported by Maden and Wakeman (1988). The published sequence differs from the genomic sequence by 1nt. U66 and the C/D box snoRNA U21 share the same host gene (RPL5).
Two copies of U66 reside in rat and mouse Rpl5 gene. In chicken and xenopus, U66 is hosted by the Zrf gene.