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 (PubMed:2686980, PubMed:1825809, PubMed:12215523). Site specificity is provided by a guide RNA that base pairs with the substrate (PubMed:2686980, PubMed:1825809). Methylation occurs at a characteristic distance from the sequence involved in base pairing with the guide RNA (PubMed:2686980, PubMed:1825809). Involved in the biogenesis of the 18S rRNA (PubMed:2686980, PubMed:1825809). 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 (PubMed:24352239). 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 Component of box C/D small nucleolar ribonucleoprotein (snoRNP) particles that contain SNU13, NOP1, SIK1/NOP56 and NOP58, plus a guide RNA. Interacts with snoRNA U3. Interacts with MPP10, NOP58, SIK1 and SOF1. Component of the ribosomal small subunit (SSU) processome composed of at least 40 protein subunits and snoRNA U3. Fibrillar region of the nucleolus. Methylated by HMT1, forming asymmetric dimethylarginines (DMA) within a domain referred to as an RGG box, made up of repeated Gly-Gly dipeptides interspersed with Arg and aromatic residues. Belongs to the methyltransferase superfamily. Fibrillarin family.