Claim: In the presence of nucleoside triphosphates and the small GTP binding protein (CPEB)3, the complex moves into the nuclear pore complex and the importin alpha enters the nucleoplasm with its passenger protein, while importin beta docks the complex at the cytoplasmic side of the nuclear pore complex.
Evidence: In the presence of nucleoside triphosphates and the small GTP binding protein Ran, the complex moves into the nuclear pore complex and the importin subunits dissociate. Ran exists in the cell in two nucleotide-bound forms: GDP-bound and GTP-bound. Ran is a small G protein that is essential for the translocation of RNA and proteins through the nuclear pore complex. In the presence of nucleoside triphosphates and the small GTP binding protein Ran, the complex moves into the nuclear pore complex and the importin subunits dissociate. Importin alpha binds the NLS-containing cargo in the cytoplasm and importin beta docks the complex at the cytoplasmic side of the nuclear pore complex.