IDENTIFICATION OF A TRANSACTIVATION FUNCTION IN THE PROGESTERONE-RECEPTOR THAT INTERACTS WITH THE TAF(II)110 SUBUNIT OF THE TFIID COMPLEX

Transcriptional activation of target genes by the human progesterone r eceptor is thought to involve direct or indirect protein-protein inter actions between the progesterone receptor and general transcription fa ctors. A key role in transcription plays the general transcription fac tor TFIID, a multiprotein complex consisting of the TATA-binding prote in and several tightly associated factors (TAFs). TAFs have been shown to be required for activated transcription and are, thus, potential t argets of activator proteins. Using in vitro interaction assays, we co uld identify specific interactions between the progesterone receptor a nd the TATA-binding protein-associated factor dTAF(II)110. The dTAF(II )110 domain responsible for the interaction is distinct from that repo rted to suffice for binding to Sp1. Somewhat surprisingly, deletion an alysis indicated that the previously identified activation functions 1 and 2 of the progesterone receptor are not required for this interact ion but pointed to an important role of the DNA binding domain. In cot ransfection experiments and an in vitro transcription assay, the DNA b inding domain of the progesterone receptor displayed significant activ ation potential. These findings, taken together, suggest that an inter action between the progesterone receptor and TAF(II)110 may represent an important step in the mechanism of activation.