Flashcards in Transcription in Eukaryotes part 2 Deck (20)
What is the C-terminal domain (CTD)?
portion of the RNA pol II responsible for helping the RNA pol leave the promoter
What are the two conformations that the CTD can take?
1. Random coil
2. Elongated version
How many times is the heptameter motif present in the CTD repeated in humans?
What is the sequence of the heptameter motif in the CTD?
what are the two roles of the heptameter motif?
1. conformational change allows polymerase to leave promoter
2. associated with mRNA procession
What is the sequence of addition of the GTFs to the DNA strand?
TFIID, TFIIB, (TFIIE, TFIIH, RNA pol 2, TFIIF)
What two elements make up TFIID?
1. TBP (TATA binding protein)
2. TAFs (TBP associated factors)
What are the characteristics and function of TFIID?
- saddle shaped
- forms H bonds with minor groove of TATA motif
- when bound to TATA motif, DNA bends underneath it
TFIID bends the DNA. Why?
Expose DNA for better binding of other transcription factors, and prevent nucleosome formation
TFIID attracts what next TF?
What is the responsibility of the TAFs, part of TFIID?
To recognize InR and DPE motifs in sequences lacking a TATA box, allowing transcription to continue
What is the main responsibility of TFIIB?
To anchor RNA pol 2 to DNA in correct orientation
What motif does TFIIB recognize?
What is the largest general transcription factor?
What are two roles of TFIIH?
1. Helicase activity to open double helix
2. Protein kinase activity responsible for phosphorylation of the serine residues on the CTD
Why is it so important for CTD of RNA pol II to become phosphorylated?
essential for RNA pol II to escape promoter
What is the role of SWI/SNF?
Clears path for promoter by modifying the path of DNA around histone octamer while also causing nucleosome sliding
What is the role of ISWI?
Clears path for promoter by sliding the histone octamers without modifying them
What is the role of SWR?
Clears path for promoter b replacing the H2A and H2B dimers with H2A.Z-H2B