TAF9b (formerly TAF9L) is a bona fide TAF that has unique and overlapping roles with TAF9

Mol Cell Biol. 2005 Jun;25(11):4638-49. doi: 10.1128/MCB.25.11.4638-4649.2005.


TFIID plays a key role in transcription initiation of RNA polymerase II preinitiation complex assembly. TFIID is comprised of the TATA box binding protein (TBP) and 14 TBP-associated factors (TAFs). A second set of transcriptional regulatory multiprotein complexes containing TAFs has been described (called SAGA, TFTC, STAGA, and PCAF/GCN5). Using matrix-assisted laser desorption ionization mass spectrometry, we identified a novel TFTC subunit, human TAF9Like, encoded by a TAF9 paralogue gene. We show that TAF9Like is a subunit of TFIID, and thus, it will be called TAF9b. TFIID and TFTC complexes in which both TAF9 and TAF9b are present exist. In vitro and in vivo experiments indicate that the interactions between TAF9b and TAF6 or TAF9 and TAF6 histone fold pairs are similar. We observed a differential induction of TAF9 and TAF9b during apoptosis that, together with their different ability to stabilize p53, points to distinct requirements for the two proteins in gene regulation. Small interfering RNA (siRNA) knockdown of TAF9 and TAF9b revealed that both genes are essential for cell viability. Gene expression analysis of cells treated with either TAF9 or TAF9b siRNAs indicates that the two proteins regulate different sets of genes with only a small overlap. Taken together, these data demonstrate that TAF9 and TAF9b share some of their functions, but more importantly, they have distinct roles in the transcriptional regulatory process.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis
  • Cell Line
  • Cell Survival / genetics
  • Cell Survival / physiology
  • Gene Expression Profiling
  • Gene Expression Regulation / physiology*
  • Humans
  • Molecular Sequence Data
  • Oligonucleotide Array Sequence Analysis
  • Protein Subunits / analysis
  • Protein Subunits / genetics
  • Protein Subunits / physiology
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / pharmacology
  • Rats
  • TATA-Binding Protein Associated Factors / analysis
  • TATA-Binding Protein Associated Factors / genetics
  • TATA-Binding Protein Associated Factors / metabolism
  • TATA-Binding Protein Associated Factors / physiology*
  • Transcription Factor TFIID / analysis
  • Transcription Factor TFIID / genetics
  • Transcription Factor TFIID / metabolism
  • Transcription Factor TFIID / physiology*
  • Transcriptional Activation
  • Tumor Suppressor Protein p53 / metabolism


  • Protein Subunits
  • RNA, Small Interfering
  • TAF9 protein, human
  • TAF9b protein, human
  • TATA-Binding Protein Associated Factors
  • Transcription Factor TFIID
  • Tumor Suppressor Protein p53