Targeting the inner nuclear membrane

Proteins destined for the inner nuclear membrane (INM) start out in the peripheral ER. Diffusion from the ER will get them to the contiguous outer nuclear membrane (ONM), but the next step could involve either vesicular transport, short-lived fusions between INM and ONM, or movement along the lipid bilayers surrounding nuclear pores. On page 1051, Ohba et al. suggest that the last explanation applies. Moreover, their data suggest that the process can only occur because the nuclear pore complex, which was thought to be a static structure, is constitutively remodeled.

Previous models suggested that INM proteins move through the nuclear pore membrane, but researchers needed a dynamic assay to test the model. By adapting a protein trapping system (Chen et al. 1995. Proc. Natl. Acad. Sci. USA. 92:4947–4951),...