DISTINCT FUNCTIONS FOR THE 2 IMPORTIN SUBUNITS IN NUCLEAR-PROTEIN IMPORT
DISTINCT FUNCTIONS FOR THE 2 IMPORTIN SUBUNITS IN NUCLEAR-PROTEIN IMPORT
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DOI：
10.1038/377246a0
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发表时间：
1995-09-21
期刊：
影响因子：
64.8
通讯作者：
LASKEY, RA
中科院分区：
文献类型：
--
作者：
GORLICH, D;VOGEL, F;LASKEY, RA
THE import of nuclear proteins proceeds through the nuclear pore complex and requires nuclear localization signals (NLSs)(1,2), energy(3,4) and soluble factors(5), namely importin-alpha (M(r) 60K)(6-12,28), importin-beta (90K)(8-11,13) and Ran(14,15). Importin-alpha is primarily responsible for NLS recognition(6-12,29) and is a member of a protein family that includes the essential yeast nuclear pore protein SRP1p (ref. 16). As the first event, the complex of importin-alpha and importin-beta binds the import substrate in the cytosols(8,9). Here we show that this nuclear pore targeting complex initially docks as a single entity to the nuclear pore via importin-beta. Then the energy-dependent, Ran-mediated translocation through the pore results in the accumulation of import substrate and importin-alpha in the nucleus. In contrast, importin-beta accumulates at the nuclear envelope, but not in the nucleoplasm. Immunoelectron microscopy detects importin-beta on both sides of the nuclear pore. This suggests that the nuclear pore targeting complex might move as a single entity from its initial docking site through the central part of the nuclear pore before it disassembles on the nucleoplasmic side.
