A Fence-like Coat for the Nuclear Pore Membrane

Abstract

We recently proposed a cylindrical coat for the nuclear pore membrane in the nuclear pore complex (NPC). This scaffold is generated by multiple copies of seven nucleoporins. Here, we report three crystal structures of the nucleoporin pair Seh1•Nup85, which is part of the coat cylinder. The Seh1•Nup85 assembly bears resemblance in its shape and dimensions to that of another nucleoporin pair, Sec13•Nup145C. Furthermore, the Seh1•Nup85 structures reveal a hinge motion that may facilitate conformational changes in the NPC during import of integral membrane proteins and/or during nucleocytoplasmic transport. We propose that Seh1•Nup85 and Sec13•Nup145C form 16 alternating, vertical rods that are horizontally linked by the three remaining nucleoporins of the coat cylinder. Shared architectural and mechanistic principles with the COPII coat indicate a common evolutionary origin and support the notion that the NPC coat represents another class of membrane coats.