IN-VITRO ASSOCIATION BETWEEN THE JUN PROTEIN FAMILY AND THE GENERAL TRANSCRIPTION FACTORS, TBP AND TFIIB

Transcriptional activator proteins interact with the general transcrip tion factors TATA-binding protein (TBP), TFIIB and/or other TBP-associ ated factors (TAFs). Using affinity chromatography we demonstrate that members of the Jun family of transcriptional activators interact with both TBP and TFIIB in vitro. TBP binds to both the N-terninal activat ion domain and C-terminal bZIP regions of c-Jun, whereas TFIIB binds t o only the c-Jun bZIP domain. This interaction requires the dimerizati on of the Jun protein. The ability of the N-terminal activation domain s of c-Jun, JunB, JunD and v-Jun to interact with TBP in vitro correla tes with their transcriptional activity in vivo. Domain mapping experi ments indicate that c-Jun interacts with the conserved C-terminus of T BP. Studies using a set of TFIIB inframe deletion mutants demonstrate that C-terminal amino acids 178-201 and 238-316 play an important role in modulating the interaction between TFIIB and c-Jun. Although phosp horylation of the c-Jun N-terminal activation domain stimulates c-Jun transcriptional activity in vivo, it has no effect on the ability of c -Jun to interact with either TBP or TFIIB in vitro. These data suggest that the Jun family of activator proteins may activate transcription by interacting with the general transcription factors TBP and TFIIB.