TY - JOUR
T1 - Bop1 is a mouse WD40 repeat nucleolar protein involved in 28S and 5.8S rRNA processing and 60S ribosome biogenesis
AU - Strezoska, Žaklina
AU - Pestov, Dimitri G.
AU - Lau, Lester F.
PY - 2000/8
Y1 - 2000/8
N2 - We have identified and characterized a novel mouse protein, Bop1, which contains WD40 repeats and is highly conserved through evolution. bop1 is ubiquitously expressed in all mouse tissues examined and is upregulated during mid-G1 in serum-stimulated fibroblasts. Immunofluorescence analysis shows that Bop1 is localized predominantly to the nucleolus. In sucrose density gradients, Bop1 from nuclear extracts cosedimerits with the 50S-80S ribonucleoprotein particles that contain the 32S rRNA precursor. RNase A treatment disrupts these particles and releases Bop1 into a low-molecular- weight fraction. A mutant form of Bop1, Bop1Δ, which lacks 231 amino acids in the N- terminus, is colocalized with wild-type Bop1 in the nucleolus and in ribonucleoprotein complexes. Expression of Bop1Δ leads to cell growth arrest in the G1 phase and results in a specific inhibition of the synthesis of the 28S and 5.8S rRNAs without affecting 18S rRNA formation. Pulse-chase analyses show that Bop1Δ expression results in a partial inhibition in the conversion of the 36S to the 32S pre-rRNA and a complete inhibition of the processing of the 32S pre-rRNA to form the mature 28S and 5.8S rRNAs. Concomitant with these defects in rRNA processing, expression of Bop1Δ in mouse cells leads to a deficit in the cytosolic 60S ribosomal subunits. These studies thus identify Bop1 as a novel, nonribosomal mammalian protein that plays a key role in the formation of the mature 28S and 5.8S rRNAs and in the biogenesis of the 60S ribosomal subunit.
AB - We have identified and characterized a novel mouse protein, Bop1, which contains WD40 repeats and is highly conserved through evolution. bop1 is ubiquitously expressed in all mouse tissues examined and is upregulated during mid-G1 in serum-stimulated fibroblasts. Immunofluorescence analysis shows that Bop1 is localized predominantly to the nucleolus. In sucrose density gradients, Bop1 from nuclear extracts cosedimerits with the 50S-80S ribonucleoprotein particles that contain the 32S rRNA precursor. RNase A treatment disrupts these particles and releases Bop1 into a low-molecular- weight fraction. A mutant form of Bop1, Bop1Δ, which lacks 231 amino acids in the N- terminus, is colocalized with wild-type Bop1 in the nucleolus and in ribonucleoprotein complexes. Expression of Bop1Δ leads to cell growth arrest in the G1 phase and results in a specific inhibition of the synthesis of the 28S and 5.8S rRNAs without affecting 18S rRNA formation. Pulse-chase analyses show that Bop1Δ expression results in a partial inhibition in the conversion of the 36S to the 32S pre-rRNA and a complete inhibition of the processing of the 32S pre-rRNA to form the mature 28S and 5.8S rRNAs. Concomitant with these defects in rRNA processing, expression of Bop1Δ in mouse cells leads to a deficit in the cytosolic 60S ribosomal subunits. These studies thus identify Bop1 as a novel, nonribosomal mammalian protein that plays a key role in the formation of the mature 28S and 5.8S rRNAs and in the biogenesis of the 60S ribosomal subunit.
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U2 - 10.1128/MCB.20.15.5516-5528.2000
DO - 10.1128/MCB.20.15.5516-5528.2000
M3 - Article
C2 - 10891491
AN - SCOPUS:0033912841
SN - 0270-7306
VL - 20
SP - 5516
EP - 5528
JO - Molecular and Cellular Biology
JF - Molecular and Cellular Biology
IS - 15
ER -