Nup98 localizes to both nuclear and cytoplasmic sides of the nuclear pore and binds to two distinct nucleoporin subcomplexes
Nup98 localizes to both nuclear and cytoplasmic sides of the nuclear pore and binds to two distinct nucleoporin subcomplexes
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DOI：
10.1091/mbc.e02-09-0582
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发表时间：
2003-02-01
影响因子：
3.3
通讯作者：
Powers, MA
中科院分区：
文献类型：
--
作者：
Griffis, ER;Xu, SL;Powers, MA
脊椎动物的核孔是一个巨大的结构，横跨核膜的双层膜。在酵母中，大多数核孔蛋白对称地分布在结构的核和细胞质两侧。然而，在脊椎动物中，大多数核孔蛋白只局限于核孔的一侧。在此，我们通过免疫荧光和免疫电子显微镜显示，Nup98存在于孔复合物的两侧。此外，我们发现Nup98的孔靶向结构域直接与细胞质核孔蛋白Nup88相互作用，Nup88是Nup214， Nup88， Nup62亚复合物的一个组成部分。Nup98先前被描述为通过直接结合Nup96与核取向的Nup160、133、107、96复合物相互作用。有趣的是，Nup98内的相同位点参与了与Nup88和Nup96的结合。这两种结合相互作用都需要Nup98 C末端的自蛋白水解裂解。当裂解被点突变阻断时，裂解位点下游至少有8个氨基酸足以阻止大多数与Nup96或Nup88的结合。因此，Nup98与核孔的两个面相互作用，这一定位与其先前描述的核细胞质穿梭活动保持一致。
The vertebrate nuclear pore is an enormous structure that spans the double membrane of the nuclear envelope. In yeast, most nucleoporins are found symmetrically on both the nuclear and cytoplasmic sides of the structure. However, in vertebrates most nucleoporins have been localized exclusively to one side of the nuclear pore. Herein, we show, by immunofluorescence and immunoelectron microscopy, that Nup98 is found on both sides of the pore complex. Additionally, we find that the pore-targeting domain of Nup98 interacts directly with the cytoplasmic nucleoporin Nup88, a component of the Nup214, Nup88, Nup62 subcomplex. Nup98 was previously described to interact with the nuclear-oriented Nup160, 133, 107, 96 complex through direct binding to Nup96. Interestingly, the same site within Nup98 is involved in binding to both Nup88 and Nup96. Autoproteolytic cleavage of the Nup98 C terminus is required for both of these binding interactions. When cleavage is blocked by a point mutation, a minimal eight amino acids downstream of the cleavage site is sufficient to prevent most binding to either Nup96 or Nup88. Thus, Nup98 interacts with both faces of the nuclear pore, a localization in keeping with its previously described nucleocytoplasmic shuttling activity.