Gene Symbol: LOS1
Description: Ran GTPase-binding protein LOS1
Alias: Ran GTPase-binding protein LOS1
Species: Saccharomyces cerevisiae S288c

Top Publications

  1. Ghavidel A, Kislinger T, Pogoutse O, Sopko R, Jurisica I, Emili A. Impaired tRNA nuclear export links DNA damage and cell-cycle checkpoint. Cell. 2007;131:915-26 pubmed
    ..that impedes the nuclear export of intron-containing tRNA via differential relocalization of the karyopherin Los1 to the cytoplasm...
  2. Karkusiewicz I, Turowski T, Graczyk D, Towpik J, Dhungel N, Hopper A, et al. Maf1 protein, repressor of RNA polymerase III, indirectly affects tRNA processing. J Biol Chem. 2011;286:39478-88 pubmed publisher
    ..Saturation of the tRNA exportin, Los1, is one reason why end-matured intron-containing pre-tRNAs accumulate in maf1? cells...
  3. Hellmuth K, Lau D, Bischoff F, Kunzler M, Hurt E, Simos G. Yeast Los1p has properties of an exportin-like nucleocytoplasmic transport factor for tRNA. Mol Cell Biol. 1998;18:6374-86 pubmed
    ..These data confirm the homology between Los1p and the recently identified human exportin for tRNA and reinforce the possibility of a role for Los1p in nuclear export of tRNA in yeast. ..
  4. Sarkar S, Hopper A. tRNA nuclear export in saccharomyces cerevisiae: in situ hybridization analysis. Mol Biol Cell. 1998;9:3041-55 pubmed
    ..Los1p is similar to exportin-t, which facilitates vertebrate tRNA export. A los1 deletion mutation affects tRNA but not poly(A) RNA export...
  5. Hurt D, Wang S, Lin Y, Hopper A. Cloning and characterization of LOS1, a Saccharomyces cerevisiae gene that affects tRNA splicing. Mol Cell Biol. 1987;7:1208-16 pubmed
    Saccharomyces cerevisiae strains carrying los1-1 mutations are defective in tRNA processing; at 37 degrees C, such strains accumulate tRNA precursors which have mature 5' and 3' ends but contain intervening sequences...
  6. Murthi A, Shaheen H, Huang H, Preston M, Lai T, Phizicky E, et al. Regulation of tRNA bidirectional nuclear-cytoplasmic trafficking in Saccharomyces cerevisiae. Mol Biol Cell. 2010;21:639-49 pubmed publisher
    ..The beta-importins involved in nuclear export have shared and exclusive functions. Los1 functions in both the tRNA primary export and the tRNA reexport processes...
  7. Hurto R, Tong A, Boone C, Hopper A. Inorganic phosphate deprivation causes tRNA nuclear accumulation via retrograde transport in Saccharomyces cerevisiae. Genetics. 2007;176:841-52 pubmed
    Nuclear export of tRNA is an essential eukaryotic function, yet the one known yeast tRNA nuclear exporter, Los1, is nonessential...
  8. Stanford D, Whitney M, Hurto R, Eisaman D, Shen W, Hopper A. Division of labor among the yeast Sol proteins implicated in tRNA nuclear export and carbohydrate metabolism. Genetics. 2004;168:117-27 pubmed
    ..cerevisiae SOL family, was previously identified as a multi-copy suppressor of the los1 defect in tRNA-mediated nonsense suppression...
  9. Feng W, Hopper A. A Los1p-independent pathway for nuclear export of intronless tRNAs in Saccharomycescerevisiae. Proc Natl Acad Sci U S A. 2002;99:5412-7 pubmed
    ..Because LOS1 is unessential in yeast, other pathways for tRNA nuclear export must exist...

More Information


  1. Grosshans H, Hurt E, Simos G. An aminoacylation-dependent nuclear tRNA export pathway in yeast. Genes Dev. 2000;14:830-40 pubmed
    ..we could show that the export of some intronless tRNA species is not detectably affected by the disruption of LOS1. To find other factors that facilitate tRNA export, we performed a suppressor screen of a synthetically lethal los1 ..
  2. McGuire A, Mangroo D. Cex1p facilitates Rna1p-mediated dissociation of the Los1p-tRNA-Gsp1p-GTP export complex. Traffic. 2012;13:234-56 pubmed publisher
    ..It is possible that this tRNA unloading mechanism is conserved in evolutionarily diverse organisms and that other Gsp1p-GTP-dependent export processes use a pathway-specific component to recruit Rna1p to the NPC. ..
  3. McGuire A, Mangroo D. Cex1p is a novel cytoplasmic component of the Saccharomyces cerevisiae nuclear tRNA export machinery. EMBO J. 2007;26:288-300 pubmed
    ..cerevisiae. They also suggest that Cex1p collects aminoacyl-tRNAs from the nuclear export receptors at the cytoplasmic side of the nuclear pore complex, and transfers them to eEF-1A using a channelling mechanism. ..
  4. Kramer E, Hopper A. Retrograde transfer RNA nuclear import provides a new level of tRNA quality control in Saccharomyces cerevisiae. Proc Natl Acad Sci U S A. 2013;110:21042-7 pubmed publisher
    ..Our data support the hypothesis that the retrograde process provides a newly discovered level of tRNA quality control as a pathway that monitors both end processing of pre-tRNAs and the modification state of mature tRNAs. ..
  5. Eswara M, Clayton A, Mangroo D. Utp22p acts in concert with Utp8p to channel aminoacyl-tRNA from the nucleolus to the nuclear tRNA export receptor Los1p but not Msn5p. Biochem Cell Biol. 2012;90:731-49 pubmed publisher
    ..It is possible that Nrap/Nol6, the mammalian orthologue of Utp22p, plays a role in channelling aminoacyl-tRNA to the nuclear tRNA export receptor exportin-t. ..
  6. Nozawa K, Ishitani R, Yoshihisa T, Sato M, Arisaka F, Kanamaru S, et al. Crystal structure of Cex1p reveals the mechanism of tRNA trafficking between nucleus and cytoplasm. Nucleic Acids Res. 2013;41:3901-14 pubmed publisher
    ..These results provide the structural basis of Los1p·Gsp1p·Cex1p·tRNA complex formation, thus clarifying the dynamic mechanism of tRNA shuttling from exportin to the translational apparatus. ..
  7. McCormick M, Delaney J, Tsuchiya M, Tsuchiyama S, Shemorry A, Sim S, et al. A Comprehensive Analysis of Replicative Lifespan in 4,698 Single-Gene Deletion Strains Uncovers Conserved Mechanisms of Aging. Cell Metab. 2015;22:895-906 pubmed publisher
    ..elegans. Among the mechanisms of aging identified, deletion of tRNA exporter LOS1 robustly extended lifespan...
  8. Shen W, Selvakumar D, Stanford D, Hopper A. The Saccharomyces cerevisiae LOS1 gene involved in pre-tRNA splicing encodes a nuclear protein that behaves as a component of the nuclear matrix. J Biol Chem. 1993;268:19436-44 pubmed
    Mutations of the Saccharomyces cerevisiae LOS1 gene cause the accumulation of end matured intron-containing pre-tRNAs at elevated temperatures...
  9. Gustavsson M, Ronne H. Evidence that tRNA modifying enzymes are important in vivo targets for 5-fluorouracil in yeast. RNA. 2008;14:666-74 pubmed publisher
    ..This suggests that tRNA destabilization contributes to 5-FU cytotoxicity in wild-type cells and provides a possible explanation why hyperthermia can enhance the effect of 5-FU in cancer therapy. ..
  10. Simos G, Sauer A, Fasiolo F, Hurt E. A conserved domain within Arc1p delivers tRNA to aminoacyl-tRNA synthetases. Mol Cell. 1998;1:235-42 pubmed
    ..These findings suggest that Arc1p operates as a mobile, trans-acting tRNA-binding synthetase domain and provide new insight into the role of eukaryotic multimeric synthetase complexes. ..
  11. Shen W, Stanford D, Hopper A. Los1p, involved in yeast pre-tRNA splicing, positively regulates members of the SOL gene family. Genetics. 1996;143:699-712 pubmed
    To understand the role of Los1p in pre-tRNA splicing, we sought los1 multicopy suppressors. We found SOL1 that suppresses both point and null LOS1 mutations...
  12. Abruzzi K, Denome S, Olsen J, Assenholt J, Haaning L, Jensen T, et al. A novel plasmid-based microarray screen identifies suppressors of rrp6Delta in Saccharomyces cerevisiae. Mol Cell Biol. 2007;27:1044-55 pubmed
    ..Microarray analyses of gene expression in rrp6Delta strains and a number of suppressor strains support this hypothesis. ..
  13. Lau D, Kunzler M, Braunwarth A, Hellmuth K, Podtelejnikov A, Mann M, et al. Purification of protein A-tagged yeast ran reveals association with a novel karyopherin beta family member, Pdr6p. J Biol Chem. 2000;275:467-71 pubmed
    ..Thus, functional tagging of yeast Ran allowed the study of its in vivo distribution and interaction with known and novel Ran-binding proteins. ..
  14. Huang H, Hopper A. Separate responses of karyopherins to glucose and amino acid availability regulate nucleocytoplasmic transport. Mol Biol Cell. 2014;25:2840-52 pubmed publisher
    The importin-? family members (karyopherins) mediate the majority of nucleocytoplasmic transport. Msn5 and Los1, members of the importin-? family, function in tRNA nuclear export...
  15. Huang H, Hopper A. In vivo biochemical analyses reveal distinct roles of β-importins and eEF1A in tRNA subcellular traffic. Genes Dev. 2015;29:772-83 pubmed publisher
    ..Our studies provide the first in vivo biochemical evidence that two β-importin family members, Los1 (exportin-t) and Msn5 (exportin-5), serve overlapping but distinct roles in tRNA nuclear export...
  16. Simos G, Tekotte H, Grosjean H, Segref A, Sharma K, Tollervey D, et al. Nuclear pore proteins are involved in the biogenesis of functional tRNA. EMBO J. 1996;15:2270-84 pubmed
    ..b>LOS1, PUS1 and NSP1 interact functionally, since the combination of mutations in the three genes causes synthetic ..
  17. Wu J, Bao A, Chatterjee K, Wan Y, Hopper A. Genome-wide screen uncovers novel pathways for tRNA processing and nuclear-cytoplasmic dynamics. Genes Dev. 2015;29:2633-44 pubmed publisher
    ..tRNA nuclear export is of particular interest because it is essential, but the known tRNA exporters (Los1 [exportin-t] and Msn5 [exportin-5]) are unessential...
  18. Chatterjee K, Majumder S, Wan Y, Shah V, Wu J, Huang H, et al. Sharing the load: Mex67-Mtr2 cofunctions with Los1 in primary tRNA nuclear export. Genes Dev. 2017;31:2186-2198 pubmed publisher
    ..The evolutionarily conserved β-importin family member Los1 (Exportin-t) has been the only exporter known to execute nuclear export of newly transcribed intron-containing pre-..