lectures 4-6

Question 1

PIC assembly steps

Answer 1

1. TFIID and TBP to TATA box
2. TFIIA, TFIIB bind TFIID
3. TFIIF and pol.II bind
4. TFIIE and TFIIH bind
5. TFIIH kinase phosphorylate CTD of pol.II

Question 2

TAR

Answer 2

inhibits P-TEFb and pauses pol.II

Question 3

TAT

Answer 3

encoded by HIV, binds to TAR

Question 4

TAT-TAR complex

Answer 4

activates P-TEFb under cell stress - viral HIV proteins are synthesized

Question 5

linker scanning reporter plasmid components

Answer 5

-multiple cloning site
-initiation complex
-ORF for enzyme
-poly A+ signal

Question 6

linker scanning reporter plasmid steps

Answer 6

1. promoter region cloned in plasmid
2. overlapping mutations introduced
3. mutant plasmids transferred to cultured cells
4. expression of reporter gene is assayed

Question 7

promoter-proximal

Answer 7

position and orientation dependent

Question 8

enhancers

Answer 8

position and orientation independent, bends DNA to be close to the promoter

Question 9

transcriptional activator

Answer 9

-binds enhancers and bends chromatin

Question 10

transcriptional activators interact with:

Answer 10

-mediator
-histone modification complex
-chromatin remodelling complex
-TAF’s

Question 11

Zn++ - finger motif

Answer 11

-DNA binding / DNA - protein interactions
-Cys / His motif

Question 12

Leu zipper motif

Answer 12

-polypeptide interactions / protein-protein
-Leu motif

Question 13

helix-turn-helix / helix-loop-helix motif

Answer 13

-polypeptide interactions

Question 14

bacteriophage 434 repressor (motif)

Answer 14

-dimeric
-helix-turn-helix interacts with one side of DNA

Question 15

C2H2 Zn-finger motif

Answer 15

-Zn2+ binding motif (2 Cys, 2 His bind 1 Zn)
-GLI DNA-binding domain - 5 C2H2 Zn fingers

Question 16

C4 Zn-finger protein

Answer 16

-4 Cys bind Zn, bind as homodimer

Question 17

B-interferon enhancer

Answer 17

-6 binding sites
-bind 2 heterodimeric factors
-bind 2 copies each of monomeric TF’s IRF-3 & IRF-7

Question 18

lipid-soluble hormones

Answer 18

diffuse through cell membrane and bind to receptor

Question 19

hormone-bound receptor

Answer 19

moves into nucleus, now an activator transcription factor

Question 20

domains of hormone receptors

Answer 20

-activation domain (N-terminal)
-DNA bind domain (Zn-finger motif)
-hormone-bind domain

Question 21

negative hormone function

Answer 21

-direct histone deacetylase to nearby nucleosomes

Question 22

positive hormone function

Answer 22

-bind histone acetylase complex to reverse repression, translocate receptor to nucleus

Question 23

hormon ligand binding steps

Answer 23

1. hormone diffuses through plasma membrane
2. replaces chaperone proteins on ligand binding domain
3. receptor translocates to nucleus, binds DNA on DNA-binding domain

Question 24

nucleosome structure

Answer 24

-8 histones (2 of each H2A, H2B, H3, H4)