Proteins of the karyopherin family that regulate the movement of proteins from the cytoplasm into the nucleus. A heterodimer of importins α and β binds the nuclear localization signals (NLS) on proteins destined for the nucleus, and importin β also binds ran-GTP and several nucleoporins that are involved in the transport process. The importins, once dissociated from their cargo, recycle to the cytoplasm. Multiple importins are known with differing predilections for their cargo. Compare exportins.
Subjects: Medicine and Health — Chemistry.