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BS3010 Gene Expression UOL > Transcription Factors > Flashcards

Flashcards in Transcription Factors Deck (18)
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1
Q

What is the definition of a transcription factor?

A

Transcription factors are adapter molecules that detect regulatory sequences in the DNA and target the assembly of protein complexes that control gene expression

2
Q

What are enhancers?

A

DNA elements that activate gene expression from a distance, irrespective of their orientation

3
Q

What are silencer elements?

A

DNA elements that repress gene expression from a distance, irrespective of their orientation.

4
Q

Properties of enhancers

A

DNaseI hypersensitive regions
P300 binding sites
Monomethylation of H3 lysine 4
Acetylation of H3 lysine 27

5
Q

What do pioneer transcription factors do?

A

Independent nucleosome / chromatin binding

Precedes other factors binding

6
Q

What are the passive roles of pioneer factors?

A

Binding speeds inductive responses
Partially bound - inactive enhancer
Induction
Fully bound - active enhancer

7
Q

What are the active roles of pioneer factors?

A

Opening chromatin

Enables other factors to be bound

8
Q

Type I receptor binding

A

Steroid receptors
Bind as homodimers
Bind in cytoplasm to HSP90
Hormone binds and completes folding of receptor
Disassociates from HSP90 and then binds to target gene in nucleus

9
Q

Type II receptor binding

A

Unliganded receptors in nucleus
Present in nucleus
May sit on target genes to repress them
Hormone binds to receptor and causes activation

10
Q

What are the two common binding domains?

A

Ligand binding domain

DNA binding domain

11
Q

What does an agonist do?

A

Activate the receptor

12
Q

What does an antagonist do?

A

Prevent activation of the receptor

13
Q

What does a partial agonist do?

A

Activate but to a lower level than agonist (can act like partial antagonists since they can compete with full agonists)

14
Q

What does an inverse agonist do?

A

Lead to inverse activity of the receptor

15
Q

What common factor do ligands have?

A

Largely non-polar character

16
Q

DNA binding domain features

A

Binds 2 zinc ions
Recognise one of two half-sites
Palindromes or direct repeats
Half-site spacing contributes to specificity

17
Q

Ligand binding domain features

A

Largely helical structure
Three layers
Ligand specificity is partly the size and shape of pocket

18
Q

What is the affect of ligand binding?

A

Complete core of the receptor
Promote dimerization and DNA binding
Stabilise position of helix 12