Class II promoter
general TF binding的順序是TFIID A B TFIIF+RNA POI II
TFIID bind 在TATA A則是在IID的上游 IIB 則是在下游連接TFIIF+RNA POI II
可是promoter介紹的地方 BRE(TFIIB recognition element)怎麼會是在TATA的上游
順便提問一下MTE (motif ten element) 是幹嘛用的?
- 7 years agoFavorite Answer
Before answering your question, you get to have a concept, that the constitution of the promoter is variable by different genes or species.
The BRE (TFIIB recognition element) is identified in 1998. BRE may be present either upstream (called BREu) or downstream (called BREd) of the TATA box. The BRE not only presents in TATA-containing promoter but more frequently in TATA-less promoter. (28.1% of a TATA-less promoters contain BREu compared to 11.8% of TATA containing promoters have BREu ).
The TFIIB have two domain, TFIIBc and TFIIBN, the TFIIB binds to the TBP(TATA box binding protein) via its c-terminus on the TATA box position. The other side, the TFIIBN binds to RNA polymerase II. These cause the DNA bended and place RNA polymerase II in position about -25 to -30(TATA box). In this moment, the TFIIB not yet get in its final position. Till the DNA is unwinded by topoisomerase, the TFIIB achieved the final position by interacting at the upstream DNA (Inr) via TFIIBN. Therefore, the TFIIB not only determine the start site of the transcription but also the direction.
The MTE is found in Drosophila, present from +18 to +27 relative to transcription start site (+1) .
MTE also functions cooperatively with the Inr and the spacing between Inr-MTE.
MTE synergistically activates transcription together with the TATA
and DPE motifs.