Figure 4.

TNPO1 has a higher affinity for FUS than TNPO3, importin β, importin 7, and importin β/7. MBP–FUS–EGFP was immobilized on GFP–Trap magnetic agarose beads and incubated with one or two His-tagged nuclear transport receptors in the presence or absence of histone H1 (A) or with two (B–E) or three (F; importin β/importin 7/TNPO1) different His-tagged nuclear transport receptors at different molar ratios, as indicated. Bound proteins were analyzed by SDS-PAGE, followed by Coomassie staining.