text: TFD is itself composed of TBP and several subunits called TATA-binding protein Associated Factors (TBP-associated factors, or TAFs). In a test tube, only TBP is necessary for transcription at promoters that contain a TATA box. TAFs, however, add promoter selectivity, especially if there is no TATA box sequence for TBP to bind to. TAFs are included in two distinct complexes, TFD and B-TFD. The TFD complex is composed of TBP and more than eight TAFs. But, the majority of TBP is present in the B-TFD complex, which is composed of TBP and TAFII170 (BTAF1) in a 1:1 ratio. TFD and B-TFD are not equivalent, since transcription reactions utilizing TFD are responsive to gene specific transcription factors such as SP1, while reactions reconstituted with B-TFD are not.
  Subunits in the TFD complex include:
  * TBP (TATA binding protein), or:
  ** TBP-related factors in animals (TBPL1; TBPL2)
  * TAF1 (TAFII250)
  * TAF2 (CIF150)
  * TAF3 (TAFII140)
  * TAF4 (TAFII130/135)
  * TAF4B (TAFII105)
  * TAF5 (TAFII100)
  * TAF6 (TAFII70/80)
  * TAF7 (TAFII55)
  * TAF8 (TAFII43)
  * TAF9 (TAFII31/32)
  * TAF9B (TAFII31L)
  * TAF10 (TAFII30)
  * TAF11 (TAFII28)
  * TAF12 (TAFII20/15)
  * TAF13 (TAFII18)
  * TAF15 (TAFII68)