The TATA-binding protein and associated factors are components of pol III transcription factor TFIIIB

Andrew K.P. Taggart, Timothy S. Fisher, B. Franklin Pugh

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RNA polymerases I, II, and III require the TATA-binding protein (TBP) to initiate promoter-specific transcription. We have separated HeLa TBP into four phosphocellulose fractions that elicit polymerase specificity in supplying TBP activity to TBP-depleted pol II and pol III transcription reactions. Polymerase specificity might arise in part through distinct TBP-associated factors (TAFs), which have recently been identified in pol I and II transcription. However, the requirement for pol III TAFs has not been established. Here we show that classical pol III transcription involves a minimum of two novel TAFs: TAF-172 and TAF-L. Not only does TAF-172 activate pol III transcription, but it also inhibits the binding of TBP to the TATA box, thereby repressing pol II transcription. The TBP-TAF-172-TAF-L complex can replace TFIIIB both in transcription reactions reconstituted with TFIIIC and in template commitment assays. Thus SL1, TFIID, and TFIIIB might be functionally similar TBP-TAF complexes that direct pol I, II, and III transcription, respectively.

Original languageEnglish (US)
Pages (from-to)1015-1028
Number of pages14
Issue number6
StatePublished - Dec 11 1992


All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)

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