Karyopherins are proteins involved in transporting molecules between the cytoplasm and the nucleus of a eukaryotic cell.
Generally, karyopherin-mediated transport occurs through nuclear pores which act as a gateway into and out of the nucleus.
They belong to the nuclear pore complex family[1] in the transporter classification database (TCDB).
[2][3] Importin beta is a variety of karyopherin that facilitates the transport of cargo proteins into the nucleus.
First, it is binding importin alpha – another type of karyopherin that binds the cargo protein in the cytoplasm—before the cargo protein is imported into the nucleus through the nuclear pore using energy derived from the Ran gradient.