TATA binding protein (TBP), along with several TBP-Associated Factors (TAF), is essential for eukaryotic transcription complex assembly. TBP-TAF complexes, such as SL1, TFIID, and TFIIB, direct the assembly of RNA polymerase (pol) I, II, and III transcription complexes, respectively. An additional TBP-TAF complex, SNAPc, is required for pol II and III mediated transcription of human snRNA genes. TAF-172 is an abundant human TBP-associated factor. It is homologous to the S. cerevisiae Mot1 ATPase which regulates transcription both negatively and positively. Both proteins are members of the Snf2/Swi2 family of DNA-targeted ATPases. Like Mot1, TAF-172 binds TBP and, via ATP hydrolysis, dissociates TBP from DNA. This hydrolysis also dissociates TAF-172 from TBP. The activity of TAF-172 requires DNA and TBP, and TAF-172 repression of TBP is reversed by TFIIA. In addition, TAF-172 inhibits TBP-driven, but not TBP-TAF-driven, pol II and III mediated transcription. Thus, TAF-172, the human homolog of yeast Mot1, functions as a positive or negative regulator of transcription by using the energy of ATP hydrolysis to target the removal of TBP from DNA.
Synonyms: TBP Associated Factor-172