Question

Confirm your knowledge: What makes transport of NES-tagged proteins directional? (out of the nucleus only) A) Exportin binds Ran-GTP in the cytoplasm, stops Exportin from re-binding NES. B) Ran-GTP is created in the nucleus, and NES cannot bind Exportin without it. C) The NES is cleaved off, so exported protein cannot re-bind Exportin.
Please HELP with these two questions and explain your reasoning

Answer 1

NES tagged protein moves out of the nucleus because the Ran-GTP created in the nucleus is necessary for binding NES bound cargo to the exportin. RAN-GTP gets dissociated in the GDP in the cytoplasm and hence it cannot transport back the cargo into the nucleus.

The arrow shows the space between the inner and outer nuclear membrane. This area is called inter membrane space.