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molecular genetics > Eukaryotic Transcription Regulation > Flashcards

Eukaryotic Transcription Regulation Flashcards

1
Q

what determines the startpoint for transcription?

A

basal apparatus

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2
Q

what determines the frequency of transcription?

A

activators

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3
Q

coactivators

A

connect activators to basal factors
- some have HAT activity and connect to SWI/SNF complexes

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4
Q

how do repressors work in eukaryotes?

A
  • sequestered in the cytoplasm
  • concentration driven by competition
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5
Q

what is the role of DNA-binding domains?

A

to bring the transcription-activation domain into the vicinity of the promoter
- DNA binding activity and transcription-activation are carried by independent domains of an activator

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6
Q

transcriptional activation motifs

A

make contact with basal factors and recruit them to the promoter

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7
Q

heat shock factor DNA binding domain

A
  • histone H1
  • helix turn helix
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8
Q

helix-turn-helix

A

triple helical cluster reinforced with beta strands
- antennapedia phenotype

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9
Q

basic leucine zipper proteins (bZIP)

A

coiled-coil dimerization domain plus a basic DNA interaction domain
- GCN4

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10
Q

basic helix-loop-helix (bHLH)

A

involved in differentiation of muscle cells

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11
Q

zinc containing DNA binding domains

A
  • zinc fingers
  • bimetal thiolate cluster
  • nuclear receptors
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12
Q

zinc fingers

A

Cys2-His 2 coordinated by a single zinc ion
- Zif268

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13
Q

bimetal thiolate cluster

A

2 zinc ions coordinated by 6 cysteines
- GAL4

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14
Q

nuclear receptors

A
  • steroids and related horomones
  • bind ligand to activate
  • 2 zinc molecules with 4 cysteins
  • gluccorticoid receptor
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15
Q

why do nuclear receptors have 2 zinc modules?

A

one for DNA interactions and the other for dimerization

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16
Q

how many zinc fingers fit into the major groove?

A

3

17
Q

acidic activation domains

A
  • cluster of negative charges
  • bulky hydrophobic residues
  • amphipathic
  • VP16 - mammalian herpes simplex virus
18
Q

what is a major class of domains found in yeast?

A

acidic activators

19
Q

glucocorticoid receptor

A

across the cellular membrane and binds to the GR. This disrupts the interaction between Hsp90 and the GR and allows the hormone/receptor complex (HR) to translocate to the nucleus where it dimerizes and binds to the promoter to target genes activating transcription.

20
Q

taxmoxifen

A
  • used to fight breast cancer
  • causes helix 12 to block p160 binding
21
Q

ligand binding domain of the estrogen receptor

A

helix 12 rotates when ligand binds
- allows p160 to bind later

22
Q

steroid activators

A

do not directly recruit members of the preinitiation
complex. Instead, they make contact with coactivatorscoactivators, which in turn,
recruit basal factors.

23
Q

mode of activator function

A
  1. p160 recruits HAT activity
  2. the estrogen receptor first recruits the CBP in the early stages of transcription and later recruits the mediator
24
Q

what do the following complexes have in common? p160, PCAF, and p300

A

all have HAT activity

25
Q

glucocorticoid, mineralcorticoid, androgen, and progesterone

A
  • form homodimers
  • all recognize TGTTCT
  • half sites are palindromes and spacing determines the element
  • head to head receptors
  • exception in TGACCT in estrogen
26
Q

thyroid, vitamin D, retinoic acid, 9-cis-retinoic acid

A
  • form heterodimers, with the exception of 9-cis which is a homodimer
  • recognize half elements TGACCT as direct repeats
  • spacing influences recognition
  • head to tail
27
Q

9-cis-retinoic acid spacing

A

1 bp

28
Q

vitamin D spacing

A

3 bp

29
Q

thyroid spacing

A

4bp

30
Q

retinoic acid spacing

A

5 bp

31
Q

SMRT co-repressor

A
  • thyroid and retinoic acid receptors bind to the SMRT corepressor at the promoter in the absence of ligand
  • binding reduces affinity for the corepressor and allows binding to coactivators
32
Q

what triggers the glucosinolate pathway in plants?

A

insect feeding

33
Q

glucosinolate pathway

A
  • insect feeding
  • synthesis of jasminate horomone
  • activates glucosinolate pathway
  • promoter repressed if no feeding, resulting in chromosome condensation and repression
  • if there is feeding, Med25 and others reduce repression and start the estrogen cycle

molecular genetics (28 decks)

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