Eukaryotic transcription initiation Flashcards
What is the GTF TFIID composed of?
TBP (TATA binding protein) and TAFs (TBP associated factors.
What is the role of the TBP subunit of TFIID
Bind to TATA box (TATAAA)
What is the role of the TAF subunits of TFIID?
Bind to initiator (Inr), MTE, DPE
What is the role of TFIIA?
Stabilizes TFIID promoter element binding.
What is the role of TFIIB?
Binds to BRE
What are the roles of TFIIF?
Stabilizes RNA polymerase interactions with TBP and TFIIB
Helps attract TFIIE and TFIIH
What is the role of TFIIE?
Attracts and regulates TFIIH
What is the role of TFIIH?
Unwinds DNA at transcription start site (helicase activity)
phosphorylates Ser5 of RNA polymerase CTD to initiate elongation (kinase activity)
Name the sequential complex of RNA polymerase II binding.
DAB-Pol-FEH
How is the D-complex of RNA polymerase binding formed?
TFIID binds MTE, DPE and Inr
How is the DA complex of RNA polymerase binding formed?
TFIIA displaces TAF1
TFIIA and TFIID (with TBP subunit) bind to TATA box
What happens after the DA complex is formed?
TFIID undergoes major conformational changes bending DNA by about 90 degrees
How is the DAB complex formed?
TFIIB binds BREu and BREd
How is the DABPolF complex formed?
TFIIF and RNA polymerase arrive
What happens after the DABPolF complex is formed?
TFIIB hooks RNA polymerase into place, TFIIF binds to DNA, helping it bind to a region from -34 to -17 and aiding in stabilization
How is the DABPolFE complex formed?
TFIIE arrives, lays over top of RNA polymerase II to secure it to the other promoters.
How is the DABPolFEH complex formed?
TFIIH attaches
What happens after the complete DABPOLFEH complex is formed?
The mediator protein binds
Describe the helicase activity of TFIIH.
TFIIH unwinds DNA using XPB and XPD subunits.
TFIIB holds the opened DNA in place as RNA polymerase II clamps on to DNA.
RNA polymerase II keeps the two strands separated.
What makes up the eukaryotic Pre-Initiation Complex (PIC)
DNA + TFIID + TFIIA + TFIIB + RNA polymerase II + TFIIF + TFIIE + TFIIH + mediator complex
What is the repeated amino acid sequence in the RNA polymerase II C-terminal domain repeat?
YSPTSPS
Describe the kinase activity of RNA polymerase II.
TFIIH phosphorylates the fifth Serine of the CTD.
What does the phosphorylation events in the CTD of RNA polymerase two signal?
Ready to enter elongation phase.
