Basic Transcription Part 6 Flashcards
1
Q
Formation of the DABPoIF (pre initiation) complex
A
- TFIID with the help of TFIIA binds TATA box and forms the DA complex
- TFIIB binds next
- TFIIF helps RNA pol bind to a region extending from -24 to+ +17
2
Q
binding of all other factors depends on
A
- TFIID binding
3
Q
TFIIB
A
- needed for TFIIF and pol to bind DABPolF
4
Q
TFIID and A
A
- protect the TATA box on the template and nontemplate strand
5
Q
TFIIF
A
- binds polymerase and brings it to DAB complex
6
Q
TFIID
A
- contains TATA-box binding proteins (TPB) + 8-10 TBP associated factors (TAFs)
7
Q
TATA-box-binding domain
A
- very rich in basic domains
- facilitates binding to DNA
8
Q
TBP
A
- binds to minor groove of DNA and forces it open
- functions with RNA pol II with a TATA box (among pol II, I, and III without TATA box)
- universal transcription factor
9
Q
Phenylalanine side chains
A
- intercalate between base pairs, causing DNA to kink
10
Q
Function of TAFs
A
- interact with promoter
- interact with gene-specific transcription factors
11
Q
some factors in TFIID
A
- necessary for interaction with upstream-activating factors, such as SP1
- also called TAF_IIS
- called coactivators
12
Q
Model for transcription enhancement by activators
A
- a minimal TBP/TAF complex fails to support activation
- Two distinct trimeric complex can support activation
- A tetrameric complex can mediate activation
- Holo-TFIID supports activation by an assortment of activators
13
Q
each transcription factor interacts with
A
- certain TAFs
14
Q
Holo-TFIID
A
- TBP + many TAFs
- interacts with several activators at once
- magnifying effect
- producing strong enhancement of transcription
15
Q
TAF enzymatic activities
A
- histone acetyltransferase
- protein kinase
16
Q
histone acetyltransferase
A
- attaches acetyl groups to lystines on histones
- usually activates transcription
17
Q
protein kinase
A
- can phosphorylate itself (TFIID) and TFIIF
- to a less extent TFIIA an TFIIE
18
Q
phosphorylation does what
A
- modifies efficiency of assembly of the pre initiation complex
19
Q
acetylation of histones does what
A
- opens DNA for transcription
20
Q
first step in formation of preinitation complex
A
- interaction of TFIID with promoter
- this is the critical step of initiation
21
Q
TFIIA bind to
A
- binds to TBP
22
Q
TFIIA major function
A
- stabilize binding between TFIID and promoter to form the DA complex
23
Q
TFIIB positioned where
A
- between TFIID and TFIIF/RNA pol
24
Q
2 domains of TFIIB
A
- one interacts with TFIID
- the other with TFIIF/RNA pol II
25
Function of TFIIB
- positions pol and transcription start site
- stabilizes TBP-TATA box binding
- interacts with transcription activators that bind upstream elements
26
gene-specific transcription factors and TFIIB
- facilitate binding of TFIIB to pre initiation complex
27
TFIIF made of
- 2 polypeptides
- RAP30
- RAP70
28
RAP
- RNA polymerase-associated protein
29
number =
- molecular mass
30
RAP30
- weak homology to E. coli sigma factor
| - mediates binding of TFIIF to the core
31
sigma like role of TFIIF
- binds to the core - analogous to sigma factor
| - reduces nonspecific interactions between polymerase and DNA
32
main role of TFIIF
- binds to polymerase and directs it to promoters containing DAB complex
33
TFIIE
- increases TFIIH activity
34
TFIIH
- phosphorylates RNA pol II
| - specifically the CTD
35
two forms of TFIIH
- Ila
| - llo
36
lla
- unphosphorylated form
| - joins pre initiation complex
37
llo
- phosphorylated enzyme
| - carries out RNA chain elongation
38
phosphorylation trigger
- trigger for polymerase to shift from initiation to elongation
39
CTD of RNA pol II
- coordinates RNA processing with transcription
40
the phosphorylated carboxy terminal domain of the large subunit of RNA polymerase II binds proteins involved in
- capping, splicing and polyadenylating precursor mRNAs.
| - all steps needed for RNA processing
41
capping enzyme
- guanylyl transferase
| - binds to phosphorylated CTD
42
splicing factors
- bind to CTD
43
components of cleavage/polyadenylation apparatus
- bind to CTD
44
2 complexes of TFIIH
- protein kinase
| - core with 2 separate DNA helicase/ATPase activities
45
TFIIE and TFIIH
- make no difference in elongation
| - required for promoter clearance
