Basic Transcription Part 6 Flashcards Preview

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Flashcards in Basic Transcription Part 6 Deck (45):
1

Formation of the DABPoIF (pre initiation) complex

1. TFIID with the help of TFIIA binds TATA box and forms the DA complex
2. TFIIB binds next
3. TFIIF helps RNA pol bind to a region extending from -24 to+ +17

2

binding of all other factors depends on

- TFIID binding

3

TFIIB

- needed for TFIIF and pol to bind DABPolF

4

TFIID and A

- protect the TATA box on the template and nontemplate strand

5

TFIIF

- binds polymerase and brings it to DAB complex

6

TFIID

- contains TATA-box binding proteins (TPB) + 8-10 TBP associated factors (TAFs)

7

TATA-box-binding domain

- very rich in basic domains
- facilitates binding to DNA

8

TBP

- 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

Phenylalanine side chains

- intercalate between base pairs, causing DNA to kink

10

Function of TAFs

- interact with promoter
- interact with gene-specific transcription factors

11

some factors in TFIID

- necessary for interaction with upstream-activating factors, such as SP1
- also called TAF_IIS
- called coactivators

12

Model for transcription enhancement by activators

- 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

each transcription factor interacts with

- certain TAFs

14

Holo-TFIID

- TBP + many TAFs
- interacts with several activators at once
- magnifying effect
- producing strong enhancement of transcription

15

TAF enzymatic activities

- histone acetyltransferase
- protein kinase

16

histone acetyltransferase

- attaches acetyl groups to lystines on histones
- usually activates transcription

17

protein kinase

- can phosphorylate itself (TFIID) and TFIIF
- to a less extent TFIIA an TFIIE

18

phosphorylation does what

- modifies efficiency of assembly of the pre initiation complex

19

acetylation of histones does what

- opens DNA for transcription

20

first step in formation of preinitation complex

- interaction of TFIID with promoter
- this is the critical step of initiation

21

TFIIA bind to

- binds to TBP

22

TFIIA major function

- stabilize binding between TFIID and promoter to form the DA complex

23

TFIIB positioned where

- between TFIID and TFIIF/RNA pol

24

2 domains of TFIIB

- 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