Nuclear Transport

Question 1

how do small molecules move through the NPC

Answer 1

freely in either direction

Question 2

how do molecules >40kDa move through the NPC

Answer 2

they are unable to pass freely
must be selectively imported/exported by an active process

Question 3

what are nucleoplasmin

Answer 3

nuclear protein
and is synthesized in the cytoplasm, as it associates with cytoplasmic filaments to translocate into the nucleus

Question 4

does nucleocytoplasmic transport via the NPC from the cytosol to nuclear transport require energy

Answer 4

yes

Question 5

what is a nuclear localization signal (NLS)

Answer 5

a specific stretch or sequence of amino acids which are recognized by nuclear receptor proteins and are both NECESSARY and SUFFICIENT for cytosol to nuclear targeting

Question 6

what does it mean for a NLS to be necessary

Answer 6

if the sequence is mutated, the modified protein fails to target to the nucleus

Question 7

what does it mean for a NLS to be sufficient

Answer 7

if the sequence linked to a non-nuclear ‘passenger’ protein is capable of redirecting the resulting fusion protein to the nucleus

Question 8

Use of small G-Proteins and an example

Answer 8

serve as molecular switches in the transport process
RAN