High levels of the GTPase Ran/TC4 relieve the requirement for nuclear protein transport factor 2
| Autor: | Bryce M. Paschal, Christian E. Fritze, Larry Gerace, Tinglu Guan |
|---|---|
| Rok vydání: | 1997 |
| Předmět: |
Heterozygote
Nucleocytoplasmic Transport Proteins Saccharomyces cerevisiae Proteins Saccharomyces cerevisiae Genes Fungal GTPase Importin Biochemistry GTP Phosphohydrolases GTP-Binding Proteins Nuclear pore Nuclear protein Genes Suppressor Molecular Biology Gene Monomeric GTP-Binding Proteins Cell Nucleus biology Genetic Complementation Test Nuclear Proteins Biological Transport Cell Biology biology.organism_classification Molecular biology Cell biology ran GTP-Binding Protein Ran Nuclear transport Carrier Proteins Gene Deletion |
| Zdroj: | The Journal of biological chemistry. 272(34) |
| ISSN: | 0021-9258 |
| Popis: | The GTPase Ran/TC4 and the 14-kDa protein nuclear transport factor 2 (NTF2) are two of the cytosolic factors that mediate nuclear protein import in vertebrates. Previous biochemical studies have shown that NTF2 binds directly to the GDP-bound form of Ran/TC4 and to proteins of the nuclear pore complex that contain phenylalanine-glycine repeats. In the present study we have used molecular genetic approaches to study the Saccharomyces cerevisiae homologue of NTF2. The scNTF2 gene encodes a protein that is 44% identical to the human protein. We found that deletion of the scNTF2 gene is lethal and that repression of NTF2p expression by a regulatable promoter results in gross structural distortions of the nuclear envelope. In a screen for high copy number suppressors of a scNTF2 deletion, the only gene we isolated other than scNTF2 itself was GSP1, the S. cerevisiae homologue of Ran/TC4. Furthermore, we found that high levels of Ran/TC4 can relieve the requirement for NTF2 in a mammalian-permeabilized cell assay for nuclear protein import. These data suggest that certain of the nuclear protein import functions of NTF2 and Ran/TC4 are closely linked and that NTF2 may serve to modulate a transport step involving Ran/TC4. |
| Databáze: | OpenAIRE |
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