FG repeats generate selectivity for NPC
The FXF repeats provide docking sites for carriers which then dig there way though. They need to have a NLS•IMP-a•IMP-b then once inside they are attacked by GTP docking with importin b.
For RNA to exit the cell a shuttling protein is required. Some of these have both NLS and NES and they target the RNA through the NPC. mRNA moves to the cytoplasm by a protein called TAP, this is a Ran independent event. tRAN requires ran through t-Exportin family. rRNA is transported out by Crm1 which also requires RAN. So most is through messenger RNA a ran independent TAP protein process.
HIV export of unspliced or partially spliced
So 3 things help export mRNA. 5 prime cap. Introns. 3 prime poly(A) tail ; and of course most important absence of introns. The 5 and 3 cap poly help to get mRNA out but are not mandatory.
Rev has a hydrophobic nuclear export signal
So if the virus wants to export its proteins it binds to the Viral Rev protein in nuclear export.
