Regulation of TFIID

TFIIA interacts directly with TBP and also with TAF11 (Kraemer et al., 2001). The interaction stabilizes the TFIID-promoter DNA complex and may induce a conformational change in TFIID that facilitates further PIC assembly (Chi and Carey, 1996). TFIIA is also a target of activators and plays an important role against many of the following inhibitory mechanisms. 

In the context of TFIID, a TAF can also function as an inhibitor of TBP-DNA interactions. The N-terminus of TAF1 has been found to interact with TBP and block TBP-DNA interaction by mimicking the surface of partially unwound minor groove of TATA box when bound to TBP (Kokubo et al., 1993 Liu et al., 1998). This inhibitory interaction is counteracted by TFIIA and by c-Jun, a transcription activator (Kokubo et al., 1998 Lively et al., 2001). 

In summary, TFIID is regulated by many factors, with both negative and positive roles. It is the integrated and counterbalanced effects of these factors that control the many important functions of TFIID. This is necessary to achieve a high level of specific regulation of gene expression in vivo. 

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Segil, N., Guermah, M., Hoffmann, A., Roeder, R.G., and Heintz, N. (1996). Mitotic regulation of TFIID Inhibition of activator-dependent transcription and changes in subcellular localization. Genes and Development 70 2389-2400. 

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