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PubMed1975

Ribosomal RNA metabolism during renal hypertrophy. Evidence of decreased degradation of newly synthesized ribosomal RNA.

The degradation rates of kidney rRNA labeled before UNI or sham are unchanged 5 days after the operations (t one-and-a half, 88 h). Therefore, there is no contribution from pre-existing rRNA to the increased amount of rRNA in the stimulated kidney. After labeling with L-(methyl-3H)methionine, the kinetics of incorporation into rRNA precursors, 10-60 min and at the postoperative times of 4, 16, 36, and 96 h. The specific activity of cytoplasmic rRNA after 1-h labeling with L-(methyl-3H)methionine increased occured at 4 or 96 h. Since (a) the rate of degradation of rRNA, (b) the kinetics of incorporation and processing of rRNA precursors, and (c) the rate of RNA synthesis appear unchanged after UNI, the accretion of rRNA must involve decreased degradation of newly synthesized rRNA.

Animals↗
PubMed1999

The interferon-inducible nucleolar p204 protein binds the ribosomal RNA-specific UBF1 transcription factor and inhibits ribosomal RNA transcription.

p204, a member of the interferon-inducible p200 family of murine proteins, is primarily nucleolar. We generated cell lines in which p204 was inducible by muristerone. This induction resulted in retardation of cell proliferation and inhibition of rRNA transcription in vivo. Interferon treatment, resulting in p204 induction and retardation of proliferation, also caused inhibition of rRNA transcription in vivo. p204 also inhibited rRNA transcription in vitro. This inhibition was overcome by addition of UBF1, the rRNA-specific transcription factor. A direct interaction between p204 and UBF1 was revealed in vitro in pull-down assays, and in vivo by co-immunoprecipitation from cell extracts. UBF1 bound strongly to at least two regions of p204: the N-terminal segment linked to the conserved 200 amino acid a segment, and the conserved 200 amino acid b segment. Cleavage of the a or b segments into two segments (encoded by single exons) resulted in a strong decrease or loss of binding. The inhibition of rRNA transcription by p204 may be due to the inhibition by p204 of the specific DNA binding of UBF1. This was revealed in electrophoretic mobility shift, magnetic bead and footprinting assays. Thus, p204 serves as a mediator of the inhibition of rRNA transcription by interferon.

Animals↗
PubMed1982

The sequence of the 5.8 S ribosomal RNA of the crustacean Artemia salina. With a proposal for a general secondary structure model for 5.8 S ribosomal RNA.

We report the primary structure of 5.8 S rRNA from the crustacean Artemia salina. The preparation shows length heterogeneity at the 5'-terminus, but consists of uninterrupted RNA chains, in contrast to some insect 5.8 S rRNAs, which consist of two chains of unequal length separated in the gene by a short spacer. The sequence was aligned with those of 11 other 5.8 S rRNAs and a general secondary structure model derived. It has four helical regions in common with the model of Nazar et al. (J. Biol. Chem. 250, 8591-8597 (1975)), but for a fifth helix a different base pairing scheme was found preferable, and the terminal sequences are presumed to bind to 28 S rRNA instead of binding to each other. In the case of yeast, where both the 5.8 S and 26 S rRNA sequences are known, the existence of five helices in 5.8 S rRNA is shown to be compatible with a 5.8 S - 26 S rRNA interaction model.

Animals↗
PubMed1980

Nucleotide sequence of 5S ribosomal RNA from Lingula anatina. A study on the molecular evolution of 5S ribosomal RNA from a living fossil.

By chromatography on columns of DEAE-Sephadex A-50 and Sephadex G-100, and electrophoresis on polyacrylamide gel, 5S rRNA was purified from a low-molecular-weight RNA fraction extracted from the total tissues of Lingula anatina. Complete digests of the 5S rRNA with RNase T1 [EC 3.1.4.8] and pancreatic RNase [EC 3.1.4.22] were sequenced by conventional column chromatography procedures. The nucleotide sequence of this RNA was determined mainly by a chemical method for sequencing the RNA 3' end-labeled with 32P (1), with the complement of the oligonucleotide catalog obtained by the complete RNase digestions of the RNA. By comparing the sequences of several invertebrate, vertebrate, and Chlorella 5S rRNAs, a phylogenic tree of the rRNAs was constructed and the time of divergence of Lingula was estimated.

Animals↗