Sandbox Reserved 709: Difference between revisions
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'''NPC'''s ('''Nuclear Pore Complexes''') are composed of many [[Nucleoporin|nucleoporins]] and are heavy proteins assembly. These complexes allow the passive diffusion of ions and the active transport of large molecules such as proteins in both directions. Because of the particular shape of NPCs, transport of large proteins take a lot of time. | '''NPC'''s ('''Nuclear Pore Complexes''') are composed of many [[Nucleoporin|nucleoporins]] and are heavy proteins assembly. These complexes allow the passive diffusion of ions and the active transport of large molecules such as proteins in both directions. Because of the particular shape of NPCs, transport of large proteins take a lot of time. | ||
Thus, proteins over 60 kDa have trouble to pass through them that’s why they need complementary proteins : '''importins''' to go in the nucleus and '''[[Exportin|exportins]]''' to go out of the nucleus. | Thus, proteins over 60 kDa have trouble to pass through them that’s why they need complementary proteins : '''[[Importin|importins]]''' to go in the nucleus and '''[[Exportin|exportins]]''' to go out of the nucleus. | ||
===Selectivity of nuclear import=== | ===Selectivity of nuclear import=== | ||
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* '''Step 7 :''' Importin α can’t leave the nucleus only with the help of Ran-GTP. It needs also interaction with '''CAS''' (''Cellular Apoptosis Susceptibility'' protein), an '''exportin''' which is similar in shape to importin β. Binding between CAS and importin α is favoured by interactions with Nup50. | * '''Step 7 :''' Importin α can’t leave the nucleus only with the help of Ran-GTP. It needs also interaction with '''CAS''' (''Cellular Apoptosis Susceptibility'' protein), an '''exportin''' which is similar in shape to importin β. Binding between CAS and importin α is favoured by interactions with Nup50. | ||
* '''Step 8 :'''The newly formed '''importin α:CAS:Ran-GTP''' complex is able to interact with nucleoplasmins of NPC, and once in the cytoplasm, Ran-GTP is hydrolysed into Ran-GDP (''see '''Step 5''' for details''). The complex splits, and importin α is now ready for a new import cycle. | * '''Step 8 :'''The newly formed '''importin α:CAS:Ran-GTP''' complex is able to interact with nucleoplasmins of NPC, and once in the cytoplasm, Ran-GTP is hydrolysed into Ran-GDP (''see '''Step 5''' for details''). The complex splits, and importin α is now ready for a new import cycle. | ||
==Importin α structure== | ==Importin α structure== | ||