β-catenin shows an overlapping sequence requirement but distinct molecular interactions for its bidirectional passage through nuclear pores

Abstract

β-Catenin is an example of a typical molecule that can be translocated bidirectionally through nuclear pore complexes (NPCs) on its own in a facilitated manner. In this work the nuclear import and export of β-catenin were examined to compare the sequence requirement of this molecule and to determine whether molecular interactions required for its bidirectional NPC passage are distinct or not. Deletion analysis of β-catenin revealed that armadillo repeats 10-12 and the C terminus comprise the minimum region necessary for nuclear migration activity. Further dissection of this fragment showed that the C terminus tail plays an essential role in nuclear migration. The region of β-catenin required for export substantially overlapped the region required for import. Therefore, the NPC translocation of β-catenin is apparently reversible, which is consistent with findings reported previously. However, different translocating molecules blocked nuclear import and export of β-catenin differentially. The data herein indicate that β-catenin shows an overlapping sequence requirement for its import and export but that bidirectional movement through the NPC proceeds through distinct molecular interactions.