title: RNA polymerase II-associated protein (RAP) 74 binds transcription factor (TF) IIB and blocks TFIIB-RAP30 binding.
abstract: A set of deletion mutants of human RNA polymerase II-associated protein (RAP) 30, the small subunit of transcription factor IIF (TFIIF; RAP30/74), was constructed to map functional domains. Mutants were tested for accurate transcriptional activity, RAP74 binding, and TFIIB binding. Transcription assays indicate the importance of both N- and C-terminal sequences for RAP30 function. RAP74 binds to the N-terminal region of RAP30 between amino acids 1 and 98. TFIIB binds to an overlapping region of RAP30, localized to amino acids 1-176 (amino acids 27-152 comprise a minimal binding region). The C-terminal region of RAP74 (amino acids 358-517) binds directly and independently to TFIIB. Interestingly, RAP74 blocks TFIIB-RAP30 binding, both by binding TFIIB and by binding RAP30. When the TFIIF complex is intact, therefore, TFIIB-TFIIF contact is maintained through RAP74. If the TFIIB-RAP30 interaction is physiologically important, the TFIIF complex must dissociate within some transcription complexes.
authors.affiliation: Department of Biochemistry, Michigan State University, East Lansing 48824, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Fang
authors.forename: Z F
authors.initials: ZF
authors.lastname: Burton
mesh_terms: D000595:Amino Acid Sequence; D006801:Humans; D008969:Molecular Sequence Data; D035581:Transcription Factor TFIIB; D014157:Transcription Factors / Q000378:metabolism*; D019473:Transcription Factors, TFII
chemical_list: D035581:Transcription Factor TFIIB; D014157:Transcription Factors; D019473:Transcription Factors, TFII; C056604:transcription factor TFIIF