Nog2p, a putative GTPase associated with pre-60S subunits and required for late 60S maturation steps.
Eukaryotic ribosome maturation depends on a set of well ordered processing steps. Here we describe the functional characterization of yeast Nog2p (Ynr053cp), a highly conserved nuclear protein. Nog2p contains a putative GTP-binding site, which is essential in vivo. Kinetic and steady-state measurements of the levels of pre-rRNAs in Nog2p-depleted cells showed a defect in 5.8S and 25S maturation and a concomitant increase in the levels of both 27SB(S) and 7S(S) precursors. We found Nog2p physically associated with large pre-60S complexes highly enriched in the 27SB and 7S rRNA precursors. These complexes contained, besides a subset of ribosomal proteins, at least two additional factors, Nog1p, another putative GTP-binding protein, and Rlp24p (Ylr009wp), which belongs to the Rpl24e family of archaeal and eukaryotic ribosomal proteins. In the absence of Nog2p, the pre-60S ribosomal complexes left the nucleolus, but were retained in the nucleoplasm. These results suggest that transient, possibly GTP-dependent association of Nog2p with the pre-ribosomes might trigger late rRNA maturation steps in ribosomal large subunit biogenesis.
Pubmed ID: 11707418 RIS Download
Active Transport, Cell Nucleus | Alternative Splicing | Amino Acid Sequence | Binding Sites | Blotting, Northern | Cell Nucleolus | Cell Nucleus | Cytoplasm | DNA, Complementary | GTP Phosphohydrolases | GTP-Binding Proteins | Genotype | Glucose | Green Fluorescent Proteins | Humans | In Situ Hybridization | Kinetics | Luminescent Proteins | Mass Spectrometry | Microscopy, Electron | Microscopy, Fluorescence | Models, Genetic | Molecular Sequence Data | Plasmids | Polyribosomes | Promoter Regions, Genetic | Protein Binding | RNA | RNA, Messenger | RNA, Ribosomal | Ribosomes | Sequence Homology, Amino Acid | Time Factors