Homo sapiens SNORD121A snoRNA. This C/D box snoRNA and its paralog SNORD121B were discovered by Yang et al. (2006) with snoSeeker. There expression was shown by Northern blot. Both are predicted to guide the 2'O-ribose methylation of 28S rRNA G4607. Methylation at this position was previously established.
Three paralogs (A1, A2 and B)reside in the platypus UBAP2 gene. In the opossum gene, A1 and A2, not B were localized.