NDC1 is a transmembrane nucleoporin that is required for NPC assembly and 
nucleocytoplasmic transport. We show here that NDC1 directly interacts with the 
nucleoporin ALADIN, mutations of which are responsible for triple-A syndrome, 
and that this interaction is required for targeting of ALADIN to nuclear pore 
complexes (NPCs). Furthermore, we show that NDC1 is required for selective 
nuclear import. Our findings suggest that NDC1-mediated localization of ALADIN 
to NPCs is essential for selective nuclear protein import, and that abrogation 
of the interaction between ALADIN and NDC1 may be important for the development 
of triple-A syndrome.