Homo sapiens ACA7 snoRNA
This H/ACA box RNA was cloned by Kiss et al. (2004) from a HeLa cell extract immunoprecipitated with an anti-GAR1 antibody. It is predicted to guide the pseudouridylation of residue U1569 and U1779 of 28S rRNA. The pseudouridylation of these residues was previously reported by Ofengand and Bakin (1997). An almost perfect copy of ACA7, ACA7B (2nt difference) resides in the RPL32P3 gene.
In Platypus, ~15,000 ACA7 full-length copies has been generated by a new retroposition mechanism. Among these, at least 21 (like PLATSINE1 shown in the Alignment) are processed into mature snoRNAs. The parental copy in the RPL32 gene appears disabled by a mutation (CCA) in the ACA box (Schmitz et al. 2008).
A potential ACA7 orthologue resides in the RPL32 gene in zebrafish, but not other fishes.