Importin 4 (IPO4)

Importin-4 is a protein encoded by the IPO4 gene. Importin is a type of protein that moves other protein molecules into the nucleus by binding to a specific recognition sequence, called the nuclear localization signal (NLS). Importin is classified as a karyopherin.

Importin has two subunits, importin α and importin β. Of these, importin α binds to the NLS of the protein to be imported to the nucleus whereas importin β helps in the docking of the importin heterodimer-bound protein to the nuclear pore complex. The NLS-Importin α-Importin β trimer dissociates after binding to Ran GTP inside the nucleus.