Peters Reiner
Institute of Medical Physics and Biophysics and Center for Nanotechnology, University of Münster, Germany.
Methods Mol Biol. 2006;322:235-58. doi: 10.1007/978-1-59745-000-3_17.
Nucleocytoplasmic transport, the exchange of matter between nucleus and cytoplasm, plays a fundamental role in human and other eukaryotic cells, affecting almost every aspect of health and disease. The only gate for the transport of small and large molecules as well as supramolecular complexes between nucleus and cytoplasm is the nuclear pore complex (NPC). The NPC is not a normal membrane transport protein (transporter). Composed of 500 to 1000 peptide chains, the NPC features a mysterious functional duality. For most molecules, it constitutes a molecular sieve with a blurred cutoff at approx 10 nm, but for molecules binding to phenylalanine-glycine (FG) motifs, the NPC appears to be a channel of approx 50 nm diameter, permitting bidirectional translocation at high speed. To achieve this, the NPC cooperates with soluble factors, the nuclear transport receptors, which shuttle between nuclear contents and cytoplasm. Here, we provide a short introduction to nucleocytoplasmic transport by describing first the structure and composition of the nuclear pore complex. Then, mechanisms of nucleocytoplasmic transport are discussed. Finally, the still essentially unresolved mechanisms by which nuclear transport receptors and transport complexes are translocated through the nuclear pore complex are considered, and a novel translocation model is suggested.
核质运输，即细胞核与细胞质之间的物质交换，在人类及其他真核细胞中发挥着基础性作用，几乎影响着健康与疾病的方方面面。细胞核与细胞质之间小分子、大分子以及超分子复合物运输的唯一通道是核孔复合体（NPC）。NPC并非普通的膜转运蛋白（转运体）。由500至1000条肽链组成的NPC具有神秘的功能双重性。对于大多数分子而言，它构成了一个截止尺寸约为10纳米的模糊的分子筛，但对于与苯丙氨酸-甘氨酸（FG）基序结合的分子，NPC似乎是一个直径约为50纳米的通道，允许双向高速转运。为实现这一点，NPC与可溶性因子即核转运受体协同作用，核转运受体在核内容物与细胞质之间穿梭。在此，我们首先描述核孔复合体的结构与组成，从而对核质运输进行简要介绍。接着，讨论核质运输的机制。最后，考虑核转运受体和转运复合物穿过核孔复合体的机制仍基本未得到解决的问题，并提出一种新的转运模型。
