TIF-IA, the factor mediating growth-dependent control of ribosomal RNA synthesis, is the mammalian homolog of yeast Rrn3p

EMBO Rep. 2000 Aug;1(2):171-5. doi: 10.1093/embo-reports/kvd032.


Cells carefully modulate the rate of rRNA transcription in order to prevent an overinvestment in ribosome synthesis under less favorable nutritional conditions. In mammals, growth-dependent regulation of RNA polymerase I (Pol I) transcription is mediated by TIF-IA, an essential initiation factor that is active in extracts from growing but not starved or cycloheximide-treated mammalian cells. Here we report the molecular cloning and functional characterization of recombinant TIF-IA, which turns out to be the mammalian homolog of the yeast factor Rrn3p. We demonstrate that TIF-IA interacts with Pol I in the absence of template DNA, augments Pol I transcription in vivo and rescues transcription in extracts from growth-arrested cells in vitro.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Amino Acid Sequence
  • Animals
  • Blotting, Western
  • Cloning, Molecular
  • Genes, Reporter / genetics
  • HeLa Cells
  • Humans
  • Mice
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Plasmids / genetics
  • Plasmids / metabolism
  • Pol1 Transcription Initiation Complex Proteins*
  • RNA, Ribosomal / biosynthesis*
  • RNA, Ribosomal / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Sequence Alignment
  • Transcription Factors / chemistry
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Transfection
  • Yeasts / genetics


  • Pol1 Transcription Initiation Complex Proteins
  • RNA, Ribosomal
  • RRN3 protein, S cerevisiae
  • RRN3 protein, human
  • Rrn3 protein, mouse
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors

Associated data

  • GENBANK/AJ272050