[PDF][PDF] TAC, a TBP-sans-TAFs complex containing the unprocessed TFIIAαβ precursor and the TFIIAγ subunit

DJ Mitsiou, HG Stunnenberg - Molecular cell, 2000 - cell.com
DJ Mitsiou, HG Stunnenberg
Molecular cell, 2000cell.com
Transcription of TATA box–containing genes by RNA polymerase II is mediated by TBP-
containing and TBP-free multisubunit complexes consisting of common and unique
components. We have identified a highly stable TBP-TFIIA-containing complex, TAC, which
is detectable in embryonal carcinoma (EC) cells but not in differentiated cells. TAC contains
the TFIIAγ subunit and the unprocessed form of TFIIAαβ, although the processed TFIIAα and
TFIIAβ subunits are present in EC cells. TAC mediates transcriptional activation by RNA …
Abstract
Transcription of TATA box–containing genes by RNA polymerase II is mediated by TBP-containing and TBP-free multisubunit complexes consisting of common and unique components. We have identified a highly stable TBP-TFIIA-containing complex, TAC, which is detectable in embryonal carcinoma (EC) cells but not in differentiated cells. TAC contains the TFIIAγ subunit and the unprocessed form of TFIIAαβ, although the processed TFIIAα and TFIIAβ subunits are present in EC cells. TAC mediates transcriptional activation by RNA polymerase II in vivo, even though it does not contain classical TAFs. Formaldehyde cross-linking revealed that in EC but not in differentiated cells, association of TBP with chromatin is strongly enhanced when complexed with TFIIA in vivo. Remarkably, the TFIIAαβ precursor is preferentially, if not exclusively, associated with chromatin as compared to the processed subunits present in "free" TFIIA in EC cells.
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