Higher Nuclear Imports and exports across the NPC

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.

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