The terminal balls characteristic of eukaryotic rRNA transcription units in chromatin spreads are rRNA processing complexes.
10.1101/gad.7.8.1609
Crossref journal-article
Cold Spring Harbor Laboratory
Genes & Development (246)
Abstract

When spread chromatin is visualized by electron microscopy, active rRNA genes have a characteristic Christmas tree appearance: From a DNA "trunk" extend closely packed "branches" of nascent transcripts whose ends are decorated with terminal "balls." These terminal balls have been known for more than two decades, are shown in most biology textbooks, and are reported in hundreds of papers, yet their nature has remained elusive. Here, we show that a rRNA-processing signal in the 5'-external transcribed spacer (ETS) of the Xenopus laevis ribosomal primary transcript forms a large, processing-related complex with factors of the Xenopus oocyte, analogous to 5' ETS processing complexes found in other vertebrate cell types. Using mutant rRNA genes, we find that the same rRNA residues are required for this biochemically defined complex formation and for terminal ball formation, analyzed electron microscopically after injection of these cloned genes into Xenopus oocytes. This, plus other presented evidence, implies that rRNA terminal balls in Xenopus, and by inference, also in the multitude of other species where they have been observed, are the ultrastructural visualization of an evolutionarily conserved 5' ETS processing complex that forms on the nascent rRNA.

Bibliography

Mougey, E. B., O’Reilly, M., Osheim, Y., Miller, O. L., Beyer, A., & Sollner-Webb, B. (1993). The terminal balls characteristic of eukaryotic rRNA transcription units in chromatin spreads are rRNA processing complexes. Genes & Development, 7(8), 1609–1619.

Authors 6
  1. E B Mougey (first)
  2. M O'Reilly (additional)
  3. Y Osheim (additional)
  4. O L Miller (additional)
  5. A Beyer (additional)
  6. B Sollner-Webb (additional)
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Dates
Type When
Created 18 years, 2 months ago (June 5, 2007, 5:15 p.m.)
Deposited 3 years, 9 months ago (Nov. 14, 2021, 9:12 p.m.)
Indexed 1 month, 1 week ago (July 11, 2025, 6:19 a.m.)
Issued 32 years ago (Aug. 1, 1993)
Published 32 years ago (Aug. 1, 1993)
Published Online 32 years ago (Aug. 1, 1993)
Published Print 32 years ago (Aug. 1, 1993)
Funders 0

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@article{Mougey_1993, title={The terminal balls characteristic of eukaryotic rRNA transcription units in chromatin spreads are rRNA processing complexes.}, volume={7}, ISSN={1549-5477}, url={http://dx.doi.org/10.1101/gad.7.8.1609}, DOI={10.1101/gad.7.8.1609}, number={8}, journal={Genes & Development}, publisher={Cold Spring Harbor Laboratory}, author={Mougey, E B and O’Reilly, M and Osheim, Y and Miller, O L and Beyer, A and Sollner-Webb, B}, year={1993}, month=aug, pages={1609–1619} }