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Updated: Jul 4, 2026

In vivo Interrogation of Central Nervous System Translatome by Polyribosome Fractionation
Published on: April 30, 2014
Pontin is localized in nucleolar fibrillar centers
Zuzana Cvacková1, Kai F Albring, Karel Koberna
1Institute of Cellular Biology and Pathology, 1st Faculty of Medicine, Charles University in Prague, Albertov 4, 128 00 Prague 2, Czech Republic.
Abstract:
Pontin is a multifunctional protein having roles in various cellular processes including regulation of gene expression. Here, we addressed Pontin intracellular localization using two different monoclonal antibodies directed against different Pontin epitopes. For the first time, Pontin was directly visualized in nucleoli where it co-localizes with Upstream Binding Factor and RNA polymerase I. Nucleolar localization of Pontin was confirmed by its detection in nucleolar extracts and by electron microscopy, which revealed Pontin accumulation specifically in the nucleolar fibrillar centers. Pontin localization in the nucleolus was dynamic and Pontin accumulated in large nucleolar dots mainly during S-phase. Pontin concentration in the large nucleolar dots correlated with reduced transcriptional activity of nucleoli. In addition, Pontin was found to associate with RNA polymerase I and to interact in a complex with c-Myc with rDNA sequences indicating that Pontin is involved in the c-Myc-dependent regulation of rRNA synthesis.
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