Guiding ribose methylation of rRNA.

Eukaryotic rRNAs contain a complex set of ribose-methylated nucleotides. Why are these nucleotides modified and how are they selected? A large family of small nucleolar RNAs (snoRNAs) with long complementarities to sites of rRNA methylation has been recently found to guide such modifications, opening up a direct approach to the study of their elusive function. Ribose methylation can also be targeted to non-rRNA sequences by tailored snoRNA guides, possibly providing a highly selective tool for altering gene expression at the post-transcriptional level.