47S pre-rRNA is nucleolytically processed at A' (01,A1), site A0, and site 02 (site 6) to yield 45S pre-rRNA

Stable Identifier
Reaction [omitted]
Homo sapiens
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Unknown nucleases concomitantly cleave the 47S precursor rRNA (pre-rRNA) at the A' site (also known as the 01 site or the A1 site), the A0 site in the 5' external transcribed spacer (5' ETS), and site 02 (also known as site 6 in mouse) in the 3' ETS (Sloan et al. 2014). Cleavage occurs when the pre-rRNA is complexed with the small subunit processome (SSU processome) complex, a large protein complex that binds the 5' region of the pre-rRNA after transcription commences (Kass and Sollner-Webb 1990, Sloan et al. 2014, inferred from yeast in Dragon et al. 2002). The UTP-A subcomplex of the SSU processome and SKIV2L2 (MTR4) are required for cleavage at the A' site while the UTP-B subcomplex and U3 snoRNP (Sloan et al. 2014) and RRP36 of the UTPC subcomplex of the SSU processome (Gerus et al. 2010) improve efficiency of cleavage. UTP18 is required for cleavage of the 5' ETS (Holzel et al. 2010). Nucleolin (NCL) interacts with the 47S pre-rRNA (Yanagida et al. 2001, inferred from mouse in Ginisty et al. 1998) and is involved in cleavage at the A' site (inferred from mouse in Ginisty et al. 1998) but its association with the SSU processome is transitory (Turner et al. 2009). NOL11, a component of the SSU processome which interacts with UTP4, increases the efficiency of processing at A', but is not strictly required (Freed et al. 2012). XRN2 exonucleolytically degrades the 5' 01 fragment (Sloan et al. 2013, inferred from mouse homologs in Wang and Pestov 2011).
Literature References
PubMed ID Title Journal Year
22916032 NOL11, implicated in the pathogenesis of North American Indian childhood cirrhosis, is required for pre-rRNA transcription and processing

Prieto, JL, McStay, B, Baserga, SJ, McCann, KL, Freed, EF

PLoS Genet. 2012
2388630 The first pre-rRNA-processing event occurs in a large complex: analysis by gel retardation, sedimentation, and UV cross-linking

Kass, S, Sollner-Webb, B

Mol. Cell. Biol. 1990
23439679 Both endonucleolytic and exonucleolytic cleavage mediate ITS1 removal during human ribosomal RNA processing

Lebaron, S, Sloan, KE, Mattijssen, S, Pruijn, GJ, Tollervey, D, Watkins, NJ

J. Cell Biol. 2013
11922599 Isolation and proteomic characterization of the major proteins of the nucleolin-binding ribonucleoprotein complexes

Nishikawa, K, Yanagida, M, Takahashi, N, Shimamoto, A, Furuichi, Y, Isobe, T

Proteomics 2001
21036871 5'-end surveillance by Xrn2 acts as a shared mechanism for mammalian pre-rRNA maturation and decay

Wang, M, Pestov, DG

Nucleic Acids Res. 2011
20056613 Defects in 18 S or 28 S rRNA processing activate the p53 pathway

Hochstatter, J, Harasim, T, Malamoussi, A, Längst, G, Eick, D, Orban, M, Rohrmoser, M, Kremmer, E, Hölzel, M

J. Biol. Chem. 2010
20038530 Evolutionarily conserved function of RRP36 in early cleavages of the pre-rRNA and production of the 40S ribosomal subunit

Bonnart, C, Caizergues-Ferrer, M, Gérus, M, Henras, AK, Henry, Y

Mol. Cell. Biol. 2010
19332556 A novel small-subunit processome assembly intermediate that contains the U3 snoRNP, nucleolin, RRP5, and DBP4

Prieto, JL, Turner, AJ, Watkins, NJ, Knox, AA, McStay, B

Mol. Cell. Biol. 2009
12068309 A large nucleolar U3 ribonucleoprotein required for 18S ribosomal RNA biogenesis

Compagnone-Post, PA, Shabanowitz, J, Wehner, KA, Wormsley, S, Baserga, SJ, Mitchell, BM, Osheim, Y, Gallagher, JE, Porwancher, KA, Settlage, RE, Dragon, F, Hunt, DF, Beyer, AL

Nature 2002
9482744 Nucleolin functions in the first step of ribosomal RNA processing

Bouvet, P, Amalric, F, Ginisty, H

EMBO J. 1998
24550520 The roles of SSU processome components and surveillance factors in the initial processing of human ribosomal RNA

Sloan, KE, Watkins, NJ, Schneider, C, Bohnsack, MT

RNA 2014
Catalyst Activity

3'-5'-exoribonuclease activity of XRN2 [nucleoplasm]

This event is regulated
Orthologous Events
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