Practice question

Box C/D small nucleolar RNAs are defined by conserved motifs Box C RUGAUGA and Box D CUGA near five prime and three prime ends that fold into kink-turn structures bound by core proteins Snu13, NOP56, NOP58, and methyltransferase fibrillarin Nop1. Each snoRNA contains antisense guide element ten to twenty-one nucleotides complementary to pre-ribosomal RNA placing target ribose five nucleotides upstream of Box D or D' for methylation. Reaction transfers methyl group from SAM to 2'-hydroxyl creating 2'-O-methyl ribose enhancing hydrophobic stacking and nuclease resistance concentrated within functional centers like peptidyl transferase loop.