Initiation of Eukaryotic Transcription

Question 1

List the transcription regulatory elements (5)

Answer 1

Core promoter, proximal promoter elements, enhancers, reporters, basal factors

Question 2

Function of core promoter

Answer 2

Contains TATA Box or CpG islands
Binding site for RNAP and GTFs

Question 3

Function of proximal promoter elements

Answer 3

Binding site for regulatory factors

Question 4

Function of reporters

Answer 4

Can be inserted into gene and assayed for activity
Ex: Luc, LacZ, GFP

Question 5

Function of Basal Factors (GTFs)

Answer 5

Everything besides RNAP that is required for transcription at core promoter

Question 6

What is the purpose of VISTA assay

Answer 6

Find conserved sequences that may be enhancer regions

Question 7

Describe structure of RNAPII and importance of CTD

Answer 7

~10 subunits
CTD essential for transcription.
Phosphorylated = initiate transcription
Unphosphorylated once leave promoter site
Requires GTFs to form PIC at core promoter

Question 8

What are the motifs contributing at the core promoter (4)

Answer 8

BRE, INR, DPE, TATA Box

Question 9

What is the BRE?

Answer 9

TFIIB Response Element
Binds TFIIB

Question 10

What is the INR?

Answer 10

Initiator
Stimulates TATA Box and binds TFIID
Can take role of TATA Box when gene lack TATA Box

Question 11

What are DPEs?

Answer 11

Downstream Promoter Elements
Further stimulate transcription

Question 12

What is the TATA Box?

Answer 12

AT rich region which positions RNAPII to focus initiation
Binds TBP (TATA Binding Protein)

Question 13

Steps of RNAPII Initiation (4)

Answer 13

1. Formation of PIC
2. Formation of Open Complex
3. Initiation
4. Promoter Clearance

Question 14

Describe the formation of the PIC at the core promoter

Answer 14

TFIID (composed of TBP + TAFs at the TATA Box) binds DNA to make more available to TFIIE/H
TFIIA/B bind to stabilize
TFIIF binds and recruits RNAPII to DNA
TFIIE/H bind

Question 15

Functions of TFIIH

Answer 15

Helicase activity to initiate transcription and kinase activity to phosphorylate RNAPII CTD

Question 16

What happens to factors after promoter clearance?

Answer 16

PIC factors release, RNAPII and TBP remain