Kutay U, Lipowsky G, Izaurralde E, Bischoff F R, Schwarzmaier P, Hartmann E, Görlich D
Zentrum für Molekulare Biologie, Universität Heidelberg, Federal Republic of Germany.
Mol Cell. 1998 Feb;1(3):359-69. doi: 10.1016/s1097-2765(00)80036-2.
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.
在真核生物中，转运RNA（tRNA）在细胞核中合成，经过几个成熟步骤后输出到细胞质中。在这里，我们确定转运蛋白t是tRNA输出的特异性介质。它是一种与RanGTP结合、与输入蛋白β相关的因子，主要定位于细胞核。它在细胞核和细胞质之间快速穿梭，并与核孔复合体相互作用。转运蛋白t直接且高亲和力地结合tRNA。通过显微注射实验判断，在非洲爪蟾卵母细胞中发现其细胞浓度是所有测试tRNA输出的限速因素。RanGTP调节底物与转运蛋白t的相互作用，使得tRNA能够优先在细胞核中结合并在细胞质中释放。
