Biochemistry Questions / Discuss the steps involved in the protein import mechanism through nuclear pore complexes.

In order to import a protein through a nuclear pore complex, it must have a nuclear import sequence. This is required to allow a karyopherin to bind, which permits the protein to be imported. The protein-karyopherin complex associates with a Ran-GDP molecule, allowing the protein to transport through the NPC. After the complex has passed through the NPC, the karyopherin dissociates from the cargo protein, binding to Ran. Ran-GEF replaces the GDP on RAN with GTP, allowing it to bind to the karyopherin, before transporting the Ran-karyopherin complex out of the nucleus to transport another cargo molecule in.