Nuclear import and export Flashcards
1
Q
NE
A
- perinuclear space (20-50nm)
2
Q
nuclear lamina
A
nuclear cytoskeleton attached to lamins
3
Q
lamins
A
intermediate filaments
4
Q
Regulatory NE functions
A
- gene expression
- QC
- selective control of nuclear content
5
Q
passive diffusion
A
- 30-60kDa polar
6
Q
NPC
A
- 500-1000 protein
- highly conserved; diameter, abundance, distribution and NUPs vary
7
Q
Symmetric core
A
- structural foundation of NPC
- cytoplasmic and nucleoplasmic rings = scaffold NUPs
8
Q
TM NUPs
A
anchor NPC to membrane
9
Q
vesicle coat, adaptin-related NUPs
A
stabilise membrane shape
10
Q
FG NUPs
A
- highly disordered
- low charge, high mean hydrophobicity
11
Q
selective
A
phase model
12
Q
asymmetric
A
- docking sites for transporter (disassembly) protein complices
13
Q
protein import
A
- histones
- lamins
- pols
- TFs
- snRPs
14
Q
protein export
A
shuttling
15
Q
karyopherin
A
conformational change upon cargo binding increases hydrophobic surfaces
16
Q
importin-beta
A
- heat repeat (approx 30-40 residues)
- amphiphilic alpha helix BD rotate
- (importin alpha adaptor protein)
17
Q
Classical NLS
A
- short stretch +ve residues (Lys, Arg)
- mono and bipartite
- bioinformatics
18
Q
multivalent binding
A
multiple FG NUPs engage with receptor surface
19
Q
RanGTPase
A
- low intrinsic activity
- small molecular switch
20
Q
NES
A
- 8-15 residue motif
- 4-5 hydrophobic residues (Leu/Val/Ile/Phe/Met) bind groove
- large array
21
Q
How does RanGDP enter nucleus?
A
Nft2
22
Q
bulk mRNA export - the basics
A
- dimeric
- human: Nfx1-Nxt1
- yeast: Mex62/Mtr2
23
Q
CBP
A
- cap binding protein
- promotes splicing
- compacts mRNA
24
Q
exon interactome
A
TREX, Dbp5
25
Dbp5
- DED-box protein 5
- helicase
26
Bulk mRNA transport - the specifics
1. mRNP diffuses from TSS to NPC (rate limiting step: secs/mins)
2. TREX, SR recruit Nxf1-Ntx1 (increases RNA affinity)
3. mRNP-Nxf1-Ntx1 docks nuclear basket (approx 100ms)
4. NPC translocation
5. Dbp5 binds Gle1
6. ATP hydrolysis; reduced RNA-affinity; Xpo-dissociation
7. Nxf1 detaches (80ms)
8. protein dissociation during translation and NPC-import
27
mRNP
mRNA-containing ribonucleoprotein
28
Nxf1-Ntf1
nuclear RNA export factor 1- ntf2-like export factor 1
29
Gle1
cytoplasmic filament NUP
30
Selective mRNA transport
1. CRM1
2. mRNP
3. cd1
4. MHC
31
nuclear envelope budding
- mega RNP granule
- perinuclear vesicles fuse ONM/ER
32
actively transcribed genes
NPC-adjacent
33
NPCs and vesicle coating complices
common ancestry
34
LECA
Ran and karyopherins
