Domain Structure in Transcription Factors Flashcards Preview

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Flashcards in Domain Structure in Transcription Factors Deck (15):
1

Domains in Transcription Factors

- Dimerization domains

- DNA-binding domains

- Activation Domains

2

 same protein 

homodimer

3

- similar, but different protein 

heterodimer

4

Dimerization domains

- protein-protein interactions -

5

DNA-binding domains

- protein-DNA interactions

- bind to DNA in sequence specific manner.

- Must be a pair of DNA binding domains in the correct conformation by dimerization of protein

6

Activation domains

- protein-protein interactions

- activate transcription or prevent transcription (gene silencing)

7

Leucine Zippers in bZIP Transcription Factors

- protein-protein domain

- Leucine at 1, 8, 15, 22 forms hydrophobic face. Two helices form a dimer based on hydrophobicity

- acts like a zipper to make 2 dimerization domains interact

 

8

bZIP

- transcription factor

- ZIP - Zipper Dimerization Domain

- b - basic (positively charged) DNA-binding domain.

- basis for interactions of negatively charged DNA

9

Leucine Zippers and DNA

- zipper is dimerization domain

- b-DNA binding domain

- activation domain

- to interact with all other proteins. located in C-terminal region.

10

Helix-Loop-Helix Transcription Factors b/HLH

- variation of leucine zipper.

- dimerization puts DNA binding domain into correct spot to bind alpha helix due to high content of basic AA - weak chemical interactions

- AA in loops act non-specifically with phosphate of DNA backbone (not dependent on sequence of DNA)

11

Specific interactions

- due to ionic and hydrogen bonds between the R groups of the amino acids and information in the major groove of DNA.

12

Zinc fingers

- DNA binding domains

- 2 cysteines (on right) , 2 histidines (on left)

- Both secondary structures represented in zinc finger

13

Tandem Repeats of Zinc Fingers

- rare to have single zinc fingers in a protein

- multiple fingers needed to interact strongly with DNA

- multiple contacts good fit

- identity of AA determine specificity of DNA binding

14

TFIIIA

- TF - transcription factor

- III - RNA pol III

- A - first discovered

15

Video

- uses zinc fingers to place genes and traits

- each additional zinc finger increases specificity.