Proteins in the karyopherin-β family mediate the majority of macromolecular 
transport between the nucleus and the cytoplasm. Eleven of the 19 known human 
karyopherin-βs and 10 of the 14S. cerevisiae karyopherin-βs mediate nuclear 
import through recognition of nuclear localization signals or NLSs in their 
cargos. This receptor-mediated process is essential to cellular viability as 
proteins are translated in the cytoplasm but many have functional roles in the 
nucleus. Many known karyopherin-β-cargo interactions were discovered through 
studies of the individual cargos rather than the karyopherins, and this 
information is thus widely scattered in the literature. We consolidate 
information about cargos that are directly recognized by import-karyopherin-βs 
and review common characteristics or lack thereof among cargos of different 
import pathways. Knowledge of karyopherin-β-cargo interactions is also critical 
for the development of nuclear import inhibitors and the understanding of their 
mechanisms of inhibition. This article is part of a Special Issue entitled: 
Regulation of Signaling and Cellular Fate through Modulation of Nuclear Protein 
Import.