Residues in the TATA-binding protein required to mediate a transcriptional response to retinoic acid in EC cells

THE eukaryotic TATA-binding protein TBP, which is required for transcription by RNA polymerase II, is tightly associated with a particular set of factors in the TFIID complex^1-5, and as such provides a target for transcriptional regulation exerted by upstream factors. An embryonic carcinoma (EC) cell-specific activity like that of the viral factor ElA has been implicated in the mediation of transactivation from the retinoic acid receptor to human TBP, but yeast TBP cannot perform this function⁶. Using TBP mutants with an altered TATA-box-binding specificity⁷, we show here that yeast TBP can mediate transcriptional activation in mammalian cells and that its inability to convey retinoic acid-dependent transactivation in EC cells is due to specific residues in its core region. These residues preclude a functional association with the cellular ElA-like activity. TBP is thus a target for retinoic acid-dependent transactivation in EC cells by providing a surface for interaction with the EC cell-specific ElA-like activity.