Meeting 15

Card Set Information

Meeting 15
2011-11-11 00:30:03

7.5 7.7
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  1. transcription by RNA pol II requires several initiation factors. These factors:
    • -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)
  2. preinitiation complex
    complex of RNA pol II and its general Tx factors bound to a promoter and ready to initiate Tx
  3. TBP (TATA-box-binding protein)
    • -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
  4. everything that happens after TBP has bound:
    • -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
  5. Another Tx factor is required for initiation by Pol II in vivo: TFIIA
    TFIIA forms a complex with TBP and TATA-box DNA
  6. TAF subunits
    -the subunits of TFIID seem to play a role in initiating Tx from promoters that LACK a TATA box
  7. downstream promoter element (DPE)
    facilitates Tx of TATA-less genes that contain it by increasing TFIID binding (and subsequently TAF activity)
  8. could do 7.7 or just review if you have time