12. Signal Transduction-Coupled Transcription Factors Flashcards Preview

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Flashcards in 12. Signal Transduction-Coupled Transcription Factors Deck (15)
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0
Q

in order to activate or repress transcription, a transcription factor must be?

A
  1. located in the nucleus

2. bind to DNA and/or interact with the basal transcriptional apparatus

1
Q

what do transcription factors do? (3 things)

A
  1. affect DNA transcription through transactivation, DNA binding (or both)
  2. have one or no DNA binding domains
  3. can be constitutive (always on) or inducible (switched on)
2
Q

adaptive responses arise from

A

inducible TFs

3
Q

what are NLSs?

A

nuclear localization signals

sequences of basic amino acids found on proteins translated by soluble ribosomes of the cytoplasm & play a critical role in nuclear transport

4
Q

transport in and out of the nucleus occurs through?

A

nuclear pores

5
Q

oily spaghetti model

A

proteins rich with Nsp-1 repeats within the nuclear pore form a gel like matrix so that smaller molecules can freely diffuse through the gaps in the matrix & larger molecules are occluded & require transportation by the proper chaperones (GTP dependent)

6
Q

what do importins do?

A

recognize NLS and facilitate transport across the nucleus

7
Q

what is the monomeric G protein that regulates transport across the nuclear envelope?

A

Ran

8
Q

regulation of ran is similar to?

A

ras

9
Q

regulation of Ran:

A

GEF: stimulates GDP dissociation (activates)
GAP: stimulates hydrolysis of bound GTP by Ran’s inherent GTPase activity

10
Q

difference between ran & ras?

A

Ran is cytoplasmic, Ras is nuclear
GTP is abundant in the nucleus, GDP is abundant in the cytoplasm

^encourages active Ran within the nucleus & inactive Ran within the cytoplasm

11
Q

Ran’s role in transport?

A

nuclear protein binds its importin, transported into the nuclear environment

GTP-Ran can bind competitively for the importins NLS binding site

binding of GTP-ran to the importin stimulates its transport back through the nuclear pore and into the cytoplasm

12
Q

all nuclear bound proteins must have a ______

A

NLS

13
Q

what is the most important part of transcription regulation?

A

transactivation

14
Q

promiscuous binding

A

one TF can bind multiple DNA sequences specifically

i.e. GC receptor, binds 2 specific DNA sequences (one is an enhancer, one is a repressor)