Meeting 15

• -position polymerase at Tx start sites
• -help melt DNA strands

• -some: TFIIA, TFIIB, and TFIID
• -TFIID is the largest and consists of TBP and 13 TAFs (TBP-associated factors)

complex of RNA pol II and its general Tx factors bound to a promoter and ready to initiate Tx

• -1st protein to bind to a TATA-box promoter
• -interacts with DNA's minor groove to bend the helix
• -C-terminal domain is pretty conserved (180 residues) while the N-terminus varies

• -once TBP has bound to promoter, TFIIB can bind
• -after TFIIB is bound, a preformed complex of TFIIF and RNA pol II attaches
• -then TFIIE binds, creating a place for TFIIH to bind
• -TFIIH subunits do 2 things: 1) one unwinds DNA so RNA pol can begin Tx and 2) a second phosphorylates the pol II CTD

TFIIA forms a complex with TBP and TATA-box DNA

-the subunits of TFIID seem to play a role in initiating Tx from promoters that LACK a TATA box

facilitates Tx of TATA-less genes that contain it by increasing TFIID binding (and subsequently TAF activity)