snoRNPs are nucleolus‐localized ribonucleoprotein particles that comprise small RNAs (snoRNAs) and a few associated proteins. Known snoRNPs can be subdivided into two major classes, C/D and H/ACA, which direct site‐specific 2′‐O‐ribose methylation and pseudouridylation of ribosomal RNA (rRNA) respectively. Some snoRNPs participate in precursor rRNA processing.

Keywords: snoRNAs; RNA modification; rRNA processing; methylation; pseudouridylation

Figure 1.

Structure of guide snoRNAs and their interaction with target RNAs. The secondary structures of the C/D‐box and H/ACA‐box snoRNAs are shown, with the conserved sequence elements and base‐paired target RNAs indicated. Most snoRNAs contain one rather than two functional domains. 2′‐O‐ribose methylation is carried out on the RNA residue that is base‐paired with the fifth position upstream from box D (or D′). Pseudouridine (ψ) formation in RNA occurs on the unpaired uridine residue upstream from the H box or the ACA box (usually 14–16 nt from the box). snoRNAs of each class are associated with a set of specific proteins that are not shown.



Bachellerie JP, Cavaillé J and Qu LH (2000) Nucleotide modifications of eukaryotic rRNAs: the world of small nucleolar RNA guides revisited. In: Garrett RA, Douthwaite SR, Liljas A, et al. (eds.) The Ribosome: Structure, Function, Antibiotics, and Cellular Interactions, pp. 191–203. Washington DC: ASM Press.

Cavaillé J, Buiting K, Kiefmann M, et al. (2000) From the cover: identification of brain‐specific and imprinted small nucleolar RNA genes exhibiting an unusual genomic organization. Proceedings of the National Academy of Sciences of the United States of America 97: 14311–14316.

Hüttenhofer A, Kiefmann M, Meier‐Ewert S, et al. (2001) RNomics: an experimental approach that identifies 201 candidates for novel, small, non‐messenger RNAs in mouse. EMBO Journal 20: 2943–2953.

Jady BE and Kiss T (2001) A small nucleolar guide RNA functions both in 2′‐O‐ribose methylation and pseudouridylation of the U5 spliceosomal RNA. EMBO Journal 20: 541–551.

Mitchell JR, Wood E and Collins K (1999) A telomerase component is defective in the human disease dyskeratosis congenita. Nature 402: 551–555.

Pogačić V, Dragon F and Filipowicz W (2000) Human H/ACA small nucleolar RNPs and telomerase share evolutionarily conserved proteins NHP2 and NOP10. Molecular and Cellular Biology 20: 9028–9040.

Tollervey D and Kiss T (1997) Function and synthesis of small nucleolar RNAs. Current Opinion in Cell Biology 9: 337–342.

Tycowski KT, You ZH, Graham PJ and Steitz JA (1998) Modification of U6 spliceosomal RNA is guided by other small RNAs. Molecular Cell 2: 629–638.

Van Eenennaam H, Jarrous N, Van Venrooij W and Pruijn GJM (2000) Architecture and function of the human endonucleases RNase P and RNase MRP. IUBMB Life 49: 1–8.

Venema J and Tollervey D (1999) Ribosome synthesis in Saccharomyces cerevisiae. Annual Review of Genetics 33: 261–311.

Watkins NJ, Segault V, Charpentier B, et al. (2000) A common core RNP structure shared between the small nucleolar box C/D RNPs and the spliceosomal U4 snRNP. Cell 103: 457–466.

Weinstein LB and Steitz JA (1999) Guided tours: from precursor snoRNA to functional snoRNP. Current Opinion in Cell Biology 11: 378–384.

Further Reading

Eddy SR (2001) Non‐coding RNA genes and the modern RNA world. Nature Reviews Genetics 2: 919–929.

Kiss T (2001) Small nucleolar RNA‐guided post‐transcriptional modification of cellular RNAs. EMBO Journal 20: 3617–3622.

Lafontaine DL and Tollervey D (1998) Birth of the snoRNPs: the evolution of the modification‐guide snoRNAs. Trends in Biochemical Sciences 23: 383–388.

Web Links

Dyskeratosis congenita 1 (DKC1); LocusID: 1736. LocusLink:

Dyskeratosis congenita 1 (DKC1); MIM number: 300126. OMIM:‐post/Omim/dispmim?300126

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Pogačić, Vanda, and Filipowicz, Witold(Sep 2005) snoRNPs. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0005031]