Transcription in Eukaryotes part 2

Question 1

What is the C-terminal domain (CTD)?

Answer 1

portion of the RNA pol II responsible for helping the RNA pol leave the promoter

Question 2

What are the two conformations that the CTD can take?

Answer 2

1. Random coil

2. Elongated version

Question 3

How many times is the heptameter motif present in the CTD repeated in humans?

Answer 3

52

Question 4

What is the sequence of the heptameter motif in the CTD?

Answer 4

tyr-ser-pro-thr-ser-pro-ser

Question 5

what are the two roles of the heptameter motif?

Answer 5

1. conformational change allows polymerase to leave promoter

2. associated with mRNA procession

Question 6

What is the sequence of addition of the GTFs to the DNA strand?

Answer 6

TFIID, TFIIB, (TFIIE, TFIIH, RNA pol 2, TFIIF)

Question 7

What two elements make up TFIID?

Answer 7

1. TBP (TATA binding protein)

2. TAFs (TBP associated factors)

Question 8

What are the characteristics and function of TFIID?

Answer 8

• saddle shaped
• forms H bonds with minor groove of TATA motif
• when bound to TATA motif, DNA bends underneath it

Question 9

TFIID bends the DNA. Why?

Answer 9

Expose DNA for better binding of other transcription factors, and prevent nucleosome formation

Question 10

TFIID attracts what next TF?

Answer 10

TFIIB

Question 11

What is the responsibility of the TAFs, part of TFIID?

Answer 11

To recognize InR and DPE motifs in sequences lacking a TATA box, allowing transcription to continue

Question 12

What is the main responsibility of TFIIB?

Answer 12

To anchor RNA pol 2 to DNA in correct orientation

Question 13

What motif does TFIIB recognize?

Answer 13

BRE

Question 14

What is the largest general transcription factor?

Answer 14

TFIIH

Question 15

What are two roles of TFIIH?

Answer 15

1. Helicase activity to open double helix

2. Protein kinase activity responsible for phosphorylation of the serine residues on the CTD

Question 16

Why is it so important for CTD of RNA pol II to become phosphorylated?

Answer 16

essential for RNA pol II to escape promoter

Question 17

What is the role of SWI/SNF?

Answer 17

Clears path for promoter by modifying the path of DNA around histone octamer while also causing nucleosome sliding

Question 18

What is the role of ISWI?

Answer 18

Clears path for promoter by sliding the histone octamers without modifying them

Question 19

What is the role of SWR?

Answer 19

Clears path for promoter b replacing the H2A and H2B dimers with H2A.Z-H2B

Question 20

What is the role of FACT?

Answer 20

Clears path for transcription of an entire gene by getting rid of H2A-H2B and recruiting histone acetyl transferases