Practice question

Chemical modification of ribosomal RNAs in eukaryotes involves predominantly 2'-O-methylation and pseudouridylation clusters concentrated in decoding center, peptidyl transferase center, and intersubunit bridges, enhancing translation accuracy and stability. These modifications are guided by small nucleolar RNAs snoRNAs residing in nucleolus and Cajal bodies that base pair via antisense elements to pre-rRNA positioning methyltransferase fibrillarin or pseudouridine synthase dyskerin. Box C/D family guides methylation while Box H/ACA guides pseudouridylation. Majority of vertebrate snoRNAs encoded within introns of protein-coding genes or noncoding gas5-like hosts, excised during splicing and assembled into snoRNPs.