S-adenosyl-L-methionine-dependent methyltransferase that has the ability to methylate both RNAs and proteins (PubMed:24352239, PubMed:30540930, PubMed:32017898). Involved in pre-rRNA processing by catalyzing the site-specific 2'-hydroxyl methylation of ribose moieties in pre-ribosomal RNA (PubMed:30540930). Site specificity is provided by a guide RNA that base pairs with the substrate (By similarity). Methylation occurs at a characteristic distance from the sequence involved in base pairing with the guide RNA (By similarity). Probably catalyzes 2'-O-methylation of U6 snRNAs in box C/D RNP complexes (PubMed:32017898). U6 snRNA 2'-O-methylation is required for mRNA splicing fidelity (PubMed:32017898). Also acts as a protein methyltransferase by mediating methylation of 'Gln-105' of histone H2A (H2AQ104me), a modification that impairs binding of the FACT complex and is specifically present at 35S ribosomal DNA locus (PubMed:24352239, PubMed:30540930). L-glutaminyl-[histone H2A] + S-adenosyl-L-methionine = H(+) + N(5)-methyl-L-glutaminyl-[histone H2A] + S-adenosyl-L-homocysteine a ribonucleotide in rRNA + S-adenosyl-L-methionine = a 2'-O-methylribonucleotide in rRNA + H(+) + S-adenosyl-L-homocysteine a ribonucleotide in U6 snRNA + S-adenosyl-L-methionine = a 2'-O-methylribonucleotide in U6 snRNA + H(+) + S-adenosyl-L-homocysteine Component of box C/D small nucleolar ribonucleoprotein (snoRNP) particles that contain SNU13, FBL, NOP5 and NOP56, plus a guide RNA (PubMed:1714385, PubMed:32017898). It is associated with the U3, U8, U13, X and Y small nuclear RNAs (PubMed:1714385). Component of several ribosomal and nucleolar protein complexes. Interacts with PRMT5 and UTP20 (PubMed:14583623, PubMed:17498821). Interacts with DDX5 and C1QBP (PubMed:10837141, PubMed:21536856). Interacts with NOL11 (PubMed:22916032). Interacts with PIH1D1 (PubMed:17636026). Interacts with RRP1B (PubMed:20926688). Interacts with NOLC1 (By similarity). Fibrillar region of the nucleolus. Ubiquitinated. Ubiquitination leads to proteasomal degradation (PubMed:19208757). Deubiquitinated by USP36 (PubMed:19208757). By homology to other fibrillarins, some or all of the N-terminal domain arginines are modified to asymmetric dimethylarginine (DMA). Acetylated by CREBBP/CBP, preventing methylation of 'Gln-105' of histone H2A (H2AQ104me), without affecting rRNA methylation (PubMed:30540930). Deacetylation by SIRT7 restores methylation of 'Gln-105' of histone H2A (H2AQ104me) (PubMed:30540930). Belongs to the methyltransferase superfamily. Fibrillarin family.