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.
Mesh Terms:
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
EMBO J.
Date: Nov. 15, 2001
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