fig1

Figure 1. Receptor-mediated nucleocytoplasmic transport of proteins. A: Illustrative overview of the nuclear import of a cargo protein bearing a "classical" NLS mediated by the Importina/Importinb heterodimer (left) and the nuclear export of a cargo protein bearing a "leucine-rich" NES mediated by XPO1 (right); B: schematic depiction of the nuclear pore complex, illustrating its main structural features; C: examples of nucleocytoplasmic transport signals. The NLSs of SV40 large T antigen (monopartite) and nucleoplasmin (bipartite) are shown, with the basic residues that characterize "classical" NLSs highlighted in red. Below, the NES of PKI and a general consensus sequence of "leucine-rich" NESs are shown. The characteristic hydrophobic residues (represented by Φ in the consensus) are highlighted in colors and underlined. NLS: nuclear localization signal; NES: nuclear export signal