Maturation of a 100 kDa protein associated with preribosomes in Chinese hamster ovary cells

Bourbon, Henri-Marc; Bugler, Béatrix; Caizergues‐Ferrer, Michèle; Amalríc, François; Zalta, J.P.

doi:10.1007/bf00777472

Cited by 56 publications

(39 citation statements)

References 31 publications

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“…An over property of the 100 kDa protein is its ability to be cleaved into specific maturation products during preribosome biogenesis. Correlations have been established between this maturation process and the transcription of pre rRNA (1,15). Taken together these results suggest that the 100 kDa protein itself and/or the process of its maturation may play a role in the regulation of ribosomal gene transcription.…”

Section: Introductionmentioning

confidence: 69%

“…After synthesis, the RNA was purified and analysed on a 5 % acrylamide urea gel. The 100 kDa protein has been purified from nucleoli as previously described (15).…”

Section: Resultsmentioning

confidence: 99%

“…Since the drug has no direct effect on RNA polymerase I activity, leupeptin must act on other nucleolar proteins. More especially it blocks the maturation of the 100 kDa protein that we have shown to be processed during preribosome biogenesis (1,15).…”

Section: Discussionmentioning

confidence: 99%

“…We would like to postulate that the 100 kDa interacts with the rDNA, the RNA polymerase and the nascent transcript and that the elongation of transcription required the cleavage of the protein and the translocation of the maturation products on nascent RNA (15).…”

Section: Discussionmentioning

confidence: 99%

“…We have used the protease inhibitor leupeptin (16) which penetrates into the cell and blocks the protease activity associated with the 100 kDa protein both "in vivo" and "in vitro" (15). "In vivo" leupeptin induces the accumulation of the 100 kDa, and inhibits the synthesis of the 45S pre rRNA.…”

Section: Introductionmentioning

confidence: 99%

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Interrelations between the maturation of a 100 kDa nucleolar protein and pre rRNA synthesis in CHO cells

et al. 1984

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The synthesis of preribosomal RNA is inhibited "in vivo" and "in vitro" by the protease inhibitor leupeptin. "In vivo" leupeptin decreases by 74 % the incorporation of labeled uridine into 45S pre rRNA while the synthesis of other RNA species is only slightly decreased. "In vitro", the elongation of already initiated pre rRNA chains that is achieved by incubation of isolated nucleoli is blocked by leupeptin. On the other hand, "in vitro" leupeptin has no direct effect on RNA polymerase I, tested in a nonspecific transcriptional system with Calf thymus DNA as template and in run off experiments with a cloned DNA containing the initiation site of the rDNA gene. A 100 kDa nucleolar protein which has been shown to be endoproteolytic cleaved "in vivo" (1) acts as an inhibitor of rDNA transcription in presence of leupeptin but produces little effect on the nonspecific transcription. In absence of the drug, the 100 kDa protein is processed in specific peptides which appeared to be similar to the "in vivo" maturation products. The possible role of the 100 kDa maturation process in the regulation of rDNA transcription is discussed. INTRODUCTIONSeveral factors have been proposed to play a role in the regulation of pre rRNA synthesis (2). In "in vivo" experiments, correLations have been estabLished between pre rRNA synthesis and the evolution of given parameters such as: aminoacid pool size (3, 4), nucleotide pool size (5), turn over of labile stimulatory protein (6) in particular ornithine decarboxylase (7), and phosphorylation of specific proteins (6). The recent development of "in vitro" systems in which a defined rDNA fragment containing the "in vivo" start site can be transcribed by RNA polymerase I, should allow the characterization of factors involved in the regulation of pre rRNA synthesis (8, 9).Such regulatory proteins must be localized in the nucleolus, a large subnuclear structure which contains most of the actively transcribed ribosomal genes in exponentially growing eukaryotic cells (10). The nascent transcripts are immediately associated with ribosomal proteins (11) and

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Section: Introductionmentioning

confidence: 69%

“…After synthesis, the RNA was purified and analysed on a 5 % acrylamide urea gel. The 100 kDa protein has been purified from nucleoli as previously described (15).…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations