SPECIES-SPECIFIC INTERACTION OF THE GLUTAMINE-RICH ACTIVATION DOMAINSOF SP1 WITH THE TATA BOX-BINDING PROTEIN

We have used protein-blotting and protein affinity chromatography to d emonstrate that each of the two glutamine-rich activation domains of t he human transcription factor Sp1 can bind specifically and directly t o the C-terminal evolutionarily conserved domain of the human TATA box -binding protein (TBP). These activation domains of Sp1 also bind dire ctly to Drosophila TBP but bind much less strongly to TBP from the yea st Saccharomyces cerevisiae. The abilities of the Sp1 activation domai ns to interact directly with the TBPs of various species correlate wel l with their abilities to activate transcription in extracts derived f rom the same species. We also show that a glutamine-rich transcription al activating region of the Drosophila protein Antennapedia binds dire ctly to TBP in a species-specific manner that reflects its ability to activate transcription in vivo. These results support the notion that TBP is a direct and important target of glutamine-rich transcriptional activators.