Identification of a tRNA-specific nuclear export receptor.
In eukaryotes, tRNAs are synthesized in the nucleus and after several maturation steps exported to the cytoplasm. Here, we identify exportin-t as a specific mediator of tRNA export. It is a RanGTP-binding, importin beta-related factor with predominantly nuclear localization. It shuttles rapidly between nucleus and cytoplasm and interacts with nuclear pore complexes. Exportin-t binds tRNA directly and with high affinity. Its cellular concentration in Xenopus oocytes was found to be rate-limiting for export of all tRNAs tested, as judged by microinjection experiments. RanGTP regulates the substrate-exportin-t interaction such that tRNA can be preferentially bound in the nucleus and released in the cytoplasm.
Kutay
U
U
Zentrum für Molekulare Biologie, Universität Heidelberg, Federal Republic of Germany.
Lipowsky
G
G
Izaurralde
E
E
Bischoff
F R
FR
Schwarzmaier
P
P
Hartmann
E
E
Görlich
D
D
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000737:chemistry* / Q000378:metabolism*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins; D009865:Oocytes / Q000502:physiology; D011485:Protein Binding / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D012343:RNA, Transfer / Q000378:metabolism*; D012345:RNA, Transfer, Amino Acid-Specific / Q000378:metabolism; D012356:RNA, Transfer, Leu / Q000378:metabolism; D012362:RNA, Transfer, Ser / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins; D028961:beta Karyopherins; D020931:ran GTP-Binding Protein
D002352:Carrier Proteins; D020690:GTPase-Activating Proteins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; C092317:RANGAP1 protein, human; D012333:RNA, Messenger; D012345:RNA, Transfer, Amino Acid-Specific; D012356:RNA, Transfer, Leu; D012362:RNA, Transfer, Ser; C513268:RanGAP1 protein, Xenopus; C503618:XPOT protein, human; D029867:Xenopus Proteins; D028961:beta Karyopherins; C091775:ran-binding protein 1; C036928:tRNA, selenocysteine-; D012343:RNA, Transfer; D019204:GTP-Binding Proteins; D020931:ran GTP-Binding Protein