Wong D H, Corbett A H, Kent H M, Stewart M, Silver P A
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
Mol Cell Biol. 1997 Jul;17(7):3755-67. doi: 10.1128/MCB.17.7.3755.
Bidirectional movement of proteins and RNAs across the nuclear envelope requires Ran, a Ras-like GTPase. A genetic screen of the yeast Saccharomyces cerevisiae was performed to isolate conditional alleles of GSP1, a gene that encodes a homolog of Ran. Two temperature-sensitive alleles, gsp1-1 and gsp1-2, were isolated. The mutations in these two alleles map to regions that are structurally conserved between different members of the Ras family. Each mutant strain exhibits various nuclear transport defects. Both biochemical and genetic experiments indicate a decreased interaction between Ntf2p, a factor which is required for protein import, and the mutant GSP1 gene products. Overexpression of NTF2 can suppress the temperature sensitive phenotype of gsp1-1 and gsp1-2 and partially rescue nuclear transport defects. However, overexpression of a mutant allele of NTF2 with decreased binding to Gsp1p cannot rescue the temperature sensitivity of gsp1-1 and gsp1-2. Taken together, these data demonstrate that the interaction between Gsp1p and Ntf2p is critical for nuclear transport.
蛋白质和RNA在核膜上的双向运输需要Ran，一种Ras样GTP酶。对酿酒酵母进行了遗传筛选，以分离GSP1的条件等位基因，GSP1是一个编码Ran同源物的基因。分离出了两个温度敏感等位基因，gsp1-1和gsp1-2。这两个等位基因中的突变定位于Ras家族不同成员之间结构保守的区域。每个突变菌株都表现出各种核运输缺陷。生化和遗传实验均表明，蛋白质导入所需的因子Ntf2p与突变的GSP1基因产物之间的相互作用减弱。NTF2的过表达可以抑制gsp1-1和gsp1-2的温度敏感表型，并部分挽救核运输缺陷。然而，与Gsp1p结合减少的NTF2突变等位基因的过表达不能挽救gsp1-1和gsp1-2的温度敏感性。综上所述，这些数据表明Gsp1p和Ntf2p之间的相互作用对核运输至关重要。
