Cse1p Is Involved in Export of Yeast Importin α from the Nucleus
Cse1p Is Involved in Export of Yeast Importin α from the Nucleus
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Cse1p 参与酵母输入蛋白 α 从细胞核的输出
DOI：
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发表时间：
1998
影响因子：
5.3
通讯作者：
G. Schlenstedt
中科院分区：
文献类型：
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作者：
J. Solsbacher;P. Maurer;F. Bischoff;G. Schlenstedt
摘要携带核定位信号的蛋白质通过异二聚体转运蛋白输入蛋白定位于细胞核。输入蛋白α与NLS和输入蛋白β结合，后者携带它通过核孔复合物（NPC）。输入蛋白在细胞核中分解，显然是通过RanGTP与输入蛋白β结合。导入子单元单独导出。我们研究了人CAS的酿酒酵母同源物Cse 1 p在酵母importin α（酵母importin α）核输出中的作用。Cse 1 p主要位于细胞核中，但也存在于细胞质和NPC中。我们分析了在野生型和cse 1 -1突变细胞中融合到绿色荧光蛋白的importin亚基的体内定位。cse 1 -1突变体在NLS输入途径中有缺陷，但在NLS非依赖性输入途径中无缺陷，在细胞核中积累了NLS 1 p而非输入蛋白β。纯化的Cse 1 p仅在RanGTP的存在下以高亲和力结合至Cse 1 p。该复合物被胞质RanGTP结合蛋白Yrb 1 p解离。结合在体内的结果，这表明，一个复合物含有Yrb 1 p，Cse 1 p，和RanGTP从细胞核输出，随后在细胞质中被分解的Yrb 1 p。NLS肽抑制了三聚体Cse 1 p-RanGTP复合物的形成，表明只有无NLS的Cse 1 p将被输出到细胞质。
ABSTRACT Proteins bearing a nuclear localization signal (NLS) are targeted to the nucleus by the heterodimeric transporter importin. Importin α binds to the NLS and to importin β, which carries it through the nuclear pore complex (NPC). Importin disassembles in the nucleus, evidently by binding of RanGTP to importin β. The importin subunits are exported separately. We investigated the role of Cse1p, theSaccharomyces cerevisiae homologue of human CAS, in nuclear export of Srp1p (yeast importin α). Cse1p is located predominantly in the nucleus but also is present in the cytoplasm and at the NPC. We analyzed the in vivo localization of the importin subunits fused to the green fluorescent protein in wild-type and cse1-1 mutant cells. Srp1p but not importin β accumulated in nuclei ofcse1-1 mutants, which are defective in NLS import but not defective in NLS-independent import pathways. Purified Cse1p binds with high affinity to Srp1p only in the presence of RanGTP. The complex is dissociated by the cytoplasmic RanGTP-binding protein Yrb1p. Combined with the in vivo results, this suggests that a complex containing Srp1p, Cse1p, and RanGTP is exported from the nucleus and is subsequently disassembled in the cytoplasm by Yrb1p. The formation of the trimeric Srp1p-Cse1p-RanGTP complex is inhibited by NLS peptides, indicating that only NLS-free Srp1p will be exported to the cytoplasm.
影响因子：
3.3
作者：
BOSSIE, MA;DEHORATIUS, C;SILVER, P
通讯作者：
SILVER, P