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 2'-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. Also acts as a protein methyltransferase by mediating methylation of 'Gln-105' of histone H2A (H2AQ105me), a modification that impairs binding of the FACT complex and is specifically present at 35S ribosomal DNA locus (By similarity). L-glutaminyl-[histone H2A] + S-adenosyl-L-methionine = H(+) + N(5)-methyl-L-glutaminyl-[histone H2A] + S-adenosyl-L-homocysteine Component of box C/D small nucleolar ribonucleoprotein (snoRNP) particles. Fibrillar region of the nucleolus. By homology to other fibrillarins, some or all of the N-terminal domain arginines are modified to asymmetric dimethylarginine (DMA). Belongs to the methyltransferase superfamily. Fibrillarin family.