Bischoff F R, Görlich D
Abteilung Molekulare Biologie der Mitose, Deutsches Krebsforschungszentrum, Heidelberg, Germany.
FEBS Lett. 1997 Dec 15;419(2-3):249-54. doi: 10.1016/s0014-5793(97)01467-1.
Nucleocytoplasmic transport appears mediated by shuttling transport receptors that bind RanGTP as a means to regulate interactions with their cargoes. The receptor-RanGTP complexes are kinetically very stable with nucleotide exchange and GTP hydrolysis being blocked, predicting that a specific disassembly mechanism exists. Here we show in three cases receptor RanGTP x RanBP1 complexes to be the key disassembly intermediates, where RanBP1 stimulates the off-rate at the receptor/RanGTP interface by more than two orders of magnitude. The transiently released RanGTP x RanBP1 complex is then induced by RanGAP to hydrolyse GTP, preventing the receptor to rebind RanGTP. The efficient release of importin beta from RanGTP requires importin alpha, in addition to RanBP1.
核质运输似乎是由穿梭运输受体介导的，这些受体结合RanGTP作为调节与货物相互作用的一种方式。受体-RanGTP复合物在动力学上非常稳定，核苷酸交换和GTP水解被阻断，这预示着存在一种特定的解离机制。在这里，我们在三种情况下表明受体RanGTP×RanBP1复合物是关键的解离中间体，其中RanBP1将受体/RanGTP界面处的解离速率提高了两个以上数量级。然后，RanGAP诱导瞬时释放的RanGTP×RanBP1复合物水解GTP，防止受体重新结合RanGTP。除了RanBP1之外，从RanGTP高效释放输入蛋白β还需要输入蛋白α。
