FIGURE 2.

Target nucleotide methylation requires a continuous, Watson–Crick paired guide:target RNA duplex. D target RNAs possessing mismatched nucleotides were incubated with in vitro assembled sR8 box C/D sRNP and 2′-O-methylation of the target nucleotide assessed. (A) Schematic presentation of sR8 D guide region with associated box D base paired to wild-type D target RNA (WT D target). Mutated WT D target RNAs are indicated below with mismatched nucleotides designated in capital letters and their distance from box D indicated in parentheses. The target nucleotide is enclosed in squares with dots indicating conserved WT D target RNA ribonucleotides. (B) Incorporation of ³H–CH₃ into D target RNAs. The level of target nucleotide methylation for each mismatched target RNA is indicated as the percent of WT D target RNA methylation.