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Human TAFII28 Interacts with the Human T Cell Leukemia Virus Type I Tax Transactivator and Promotes its Transcriptional Activity

Cecile Caron, Gabrielle Mengus, Veronica Dubrowskaya, Armelle Roisin, Irwin Davidson and Pierre Jalinot
Proceedings of the National Academy of Sciences of the United States of America
Vol. 94, No. 8 (Apr. 15, 1997), pp. 3662-3667
Stable URL: http://www.jstor.org/stable/41886
Page Count: 6
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Human TAFII28 Interacts with the Human T Cell Leukemia Virus Type I Tax Transactivator and Promotes its Transcriptional Activity
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Abstract

The Tax protein encoded by human T cell leukemia virus type I transactivates the viral promoter by forming a complex with several cellular factors bound to three repeats of a specific upstream regulatory sequence. We have shown that transactivation by Tax was correlated with its ability to interact with the C-terminal moiety of the TATA box-binding protein (TBP). In the present study, the ability of Tax to interact with several human TBP-associated factors (TAFIIs) was analyzed. We show that Tax interacts selectively with hTAFII28 in transfected HeLa cells. A direct interaction between Tax and hTAFII28 was also observed in vitro with purified proteins. In transient expression studies we show that overexpression of hTAFII28 significantly increased transactivation by Tax, both in the absence and in the presence of overexpressed TBP. The ability of hTAFII28 to potentiate transactivation correlated with the ability of Tax to interact with hTAFII28 and also with the ability of hTAFII28 to interact with TBP. Coexpression of TBP and hTAFII28 resulted in an additive increase in transactivation by Tax. From these observations we propose that transcriptional activation by Tax involves multiple interactions with TFIID via its TBP and hTAFII28 subunits.

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