rRNA 2'-O-methyltransferase fibrillarin (FBL)

S-adenosyl-L-methionine-dependent methyltransferase that has the ability to methylate both RNAs and proteins. Involved in pre-rRNA processing by catalyzing the site-specific two'-hydroxyl methylation of ribose moieties in pre-ribosomal RNA.

Site specificity is provided by a guide RNA that base pairs with the substrate. Methylation occurs at a characteristic distance from the sequence involved in base pairing with the guide RNA.