week 3 reading

Question 1

importin: entering nucleus

Answer 1

carries NLS-attached cargo into nucleus

Question 2

Ran-GTP and importin

Answer 2

Ran-GTP binds importin when it is in nucleus
alters NLS binding site, importin loses affinity for NLS

Question 3

importin: exiting nucleus

Answer 3

Ran-GTP bound importin is shuttled out via NPC

Question 4

Ran-GTP and importin in cytosol

Answer 4

Ran-GTP hydrolyzed to Ran-GDP
I loses affinity, exposing NLS binding site

Question 5

exportin: exiting nucleus

Answer 5

exportin binds Ran-GTP and NES at the same time and is shuttled out via NPC

Question 6

Ran-GTP and exportin in cytosol

Answer 6

Ran-GTP hydrolyzed, cargo released with shape change
E reenters nucleus

Question 7

Ran-GEF location and function

Answer 7

nucleus
converts Ran-GDP to Ran-GTP

Question 8

Ran-GAP location and function

Answer 8

cytosol
hydrolyzes Ran-GTP to Ran-GDP

Question 9

sec61: transport process

Answer 9

free ribosomes bind SRP
SRP blocks translation to deliver mRNA, ribosome, protein complex through Sec61
signal sequence is cleaved by protease, N-terminus faces cytosol and C-terminus moves through Sec61

Question 10

misfolded proteins

Answer 10

retrotranslocon unfolds and transfers back to cytosol
Ub binds signal polypeptide to go through proteasome
single AAs recovered