Amino acid sequence of several known nuclear targeting sequences. (A) Classical Nuclear Localization Signals. Nuclear import signals of cargos (B) up-regulated and (C) down-regulated by phosphorylation. Colored in blue are basic amino acids within the import signal, usually critical for recognition by karyopherins. In red are sites of phosphorylation that have been shown to modulate nuclear import.
Nardozzi et al. Cell Communication and Signaling 2010 8:32 doi:10.1186/1478-811X-8-32