Where no RNA polymerase has gone before: Novel functional transcripts derived from the ribosomal intergenic spacer

Mathieu D. Jacob, Timothy E. Audas, Sahra Taylor Mullineux, Stephen Lee

Research output: Contribution to journalArticle

21 Scopus citations


The nucleolus is organized around a scaffolding of rDNA tandem repeats. These repeats, known as ribosomal cassettes, are each composed of ribosomal RNA (rRNA) genes preceding a long intergenic spacer (IGS) that has been classically perceived to be transcriptionally silent. Recent study of the IGS has contradicted the dogma that these spacers are merely inert regions of the genome, instead suggesting they are biologically significant, complex and plurifunctional transcriptional units that appear central to proper cellular functioning. Through the timely induction of various ribosomal IGS noncoding RNA (IGS RNA) transcripts, the cell is capable of both regulating rRNA synthesis and sequestering large numbers of proteins, thereby modulating essential molecular networks. Here we discuss our current understanding of the organization and function of the IGS.

Original languageEnglish (US)
Pages (from-to)315-319
Number of pages5
JournalNucleus (United States)
Issue number4
StatePublished - Jan 1 2012



  • Noncoding RNA
  • Nucleolar sequestration
  • Nucleolus
  • Protein immobilization
  • RNA polymerase
  • Ribosomal intergenic spacer
  • ribosomal DNA

ASJC Scopus subject areas

  • Cell Biology

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