title: Interaction between the small GTPase Ran/Gsp1p and Ntf2p is required for nuclear transport.
abstract: 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.
authors.affiliation: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Dana-Farber Cancer Institute, Boston, Massachusetts 02115, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Wong
authors.forename: A H
authors.initials: AH
authors.lastname: Corbett
authors.forename: H M
authors.initials: HM
authors.lastname: Kent
authors.forename: M
authors.initials: M
authors.lastname: Stewart
authors.forename: P A
authors.initials: PA
authors.lastname: Silver
mesh_terms: D000595:Amino Acid Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D020559:Monomeric GTP-Binding Proteins; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D029543:Nucleocytoplasmic Transport Proteins; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D013329:Structure-Activity Relationship; D020931:ran GTP-Binding Protein
chemical_list: D002352:Carrier Proteins; D005656:Fungal Proteins; C080324:GSP1 protein, S cerevisiae; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; D019204:GTP-Binding Proteins; D020559:Monomeric GTP-Binding Proteins; D020931:ran GTP-Binding Protein