Frey Steffen, Görlich Dirk
Max-Planck-Institut für Biophysikalische Chemie, Am Fassberg 11, D-37077 Göttingen, Germany.
Cell. 2007 Aug 10;130(3):512-23. doi: 10.1016/j.cell.2007.06.024.
The permeability barrier of nuclear pore complexes (NPCs) controls the exchange between nucleus and cytoplasm. It suppresses the flux of inert macromolecules > or = 30 kDa but allows rapid passage of even very large cargoes, provided these are bound to appropriate nuclear transport receptors. We show here that a saturated hydrogel formed by a single nucleoporin FG-repeat domain is sufficient to reproduce the permeability properties of NPCs. Importin beta and related nuclear transport receptors entered such hydrogel >1000x faster than a similarly sized inert macromolecule. The FG-hydrogel even reproduced import signal-dependent and importin-mediated cargo influx, allowing importin beta to accelerate the gel entry of a large cognate cargo more than 20,000-fold. Intragel diffusion of the importin beta-cargo complex occurred rapidly enough to traverse an NPC within approximately 12 ms. We extend the "selective phase model" to explain these effects.
核孔复合体（NPC）的通透屏障控制着细胞核与细胞质之间的物质交换。它抑制分子量大于或等于30 kDa的惰性大分子的通量，但允许即使非常大的货物快速通过，前提是这些货物与适当的核转运受体结合。我们在此表明，由单个核孔蛋白FG重复结构域形成的饱和水凝胶足以重现NPC的通透特性。输入蛋白β及相关核转运受体进入这种水凝胶的速度比同样大小的惰性大分子快1000倍以上。FG水凝胶甚至重现了依赖输入信号和输入蛋白介导的货物内流，使输入蛋白β能将大型同源货物的凝胶进入速度加快20000倍以上。输入蛋白β-货物复合物在凝胶内的扩散速度足够快，大约12毫秒内就能穿过一个NPC。我们扩展了“选择性相模型”来解释这些效应。
