Import and Export from the Nucleus Flashcards Preview

Molecules to Medicine III > Import and Export from the Nucleus > Flashcards

Flashcards in Import and Export from the Nucleus Deck (17)
1

Name at least 8 types of molecules that are imported and exported from the nucleus

Imported:
RNA polymerases
DNA polymerases
Protein kinases/ phosphates
Histones
RNA binding proteins
snRNAs
Transcription factors

Exported:
60s and 40s Ribosomal subunits
tRNA
mRNA
RNA binding proteins
snRNAs
Transcription factors

2

What are the 3 layers of the Nuclear pore complex (NPC)?

Cytoplasm -> barrier layer -> scaffold layer -> membrane layer -> nucleus

3

What distinct proteins help to form the subcomplexes of NPCs?

Nucleoporins (nups)

4

What feature helps proteins enter neucleus?

Ability to interact with FG repeat -> bind and gradually move into cell

5

What are the two important types of karyopherin import receptors?

karyopherin Beta (beta-importin - cargo specific)
heterodimeric import receptors (Alpha and beta importins - work together to bring in proteins)

6

Where is RanGTP located? RanGDP?

RanGTP: nucleus
RanGDP: cytoplasm

7

What happens when an importin bound to its cargo encounters RanGTP?

Releases cargo

8

What is required fro exportins to bind their cargo?

RanGTP

9

What are the targeting signals for molecules bound in or out of the nucleus?

In: Nuclear localization signal NLS
Out: Nuclear export signal NES

10

What types of pathological conditions can nuclear trafficking defects cause?

developmental defects
cancer
infectious disease
autoimmunity
cardiac disease
neurodegenerative disease (AD & ALS)

11

What pathology does human Nup 155 cause?

AF -> cardiac disorder characerized by clinical arrhythmia

12

What pathology does human Nup 62 cause?

Autosomal recessive infantile bilateral striatal necrosis (degeneration of basal ganglia

13

What pathology does human Nup 358/ RanBP2 cause?

familial cases of infection acute necrotizing encephalophathy

14

What pathology does human Nup88 cause?

breast and ovaian cancers

15

Name at least 3 mechanisms of regulating nuclear transport

stimulation dependent nucleocytoplasmic transport
- binding on surface of cell triggers/ inhibits import/export

Intramolecular masking
- fold protein so NES/NLS not visible

Intermollecular masking
- bind to substrate that conceals NLS/NES

Affinity enhancement
- add cofactors to increase binding affinity

sequestration

binding to cytoskeleton

binding to chromatin

16

How does male to female sex reversal occur?

when mutates SRY region cannot enter nucleus -> cannot initiate transcription of male genes

17

How are Nups related to cancer?

Often fused in cancerous cells
-lead to unregulated expression?