Nuclear Pore Basket Proteins Are Tethered to the Nuclear Envelope and Can Regulate Membrane Curvature

Nuclear pore complexes (NPCs) are selective transport channels embedded in the nuclear envelope. The cylindrical NPC core forms a protein coat lining a highly curved membrane opening and has a basket-like structure appended to the nucleoplasmic side. How NPCs interact with lipids, promoting membrane bending and NPC integrity, is poorly understood. Here we show that the NPC basket proteins Nup1 and Nup60 directly induce membrane curvature by amphipathic helix insertion into the lipid bilayer. In a cell-free system, both Nup1 and Nup60 transform spherical liposomes into highly curved membrane structures. In vivo, high levels of the Nup1/Nup60 amphipathic helices cause deformation of the yeast nuclear membrane, whereas adjacent helical regions contribute to anchoring the basket to the NPC core. Basket amphipathic helices are functionally linked to distinct transmembrane nucleoporins of the NPC core, suggesting a key contribution to the membrane remodeling events that underlie NPC assembly.