Ядерный транспорт в клетке
Sep. 28th, 2010 12:30 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
imbgЧтобы проследить на более точном уровне систему транспорта молекул через ядерную мембрану, исследователи из Калифорнийского университета провели серию экспериментов с меченными квантовыми точками (quantunm dot) белками; они позволили визуализировать процес переноса белков по ядерным порам. Оказалось, что процес импорта веществ в ядро состоит из нескольких стадий; все эти стадии обратимы, кроме одной, последней, — выброса груза внутрь ядра.
Абстракт статьи в Nature:
Selectivity mechanism of the nuclear pore complex characterized by single cargo tracking
Alan R. Lowe, Jake J. Siegel, Petr Kalab, Merek Siu, Karsten Weis & Jan T. Liphardt
Nature (2010) doi:10.1038/nature09285
Received 15 November 2009 Accepted 10 June 2010 Published online 01 September 2010
The nuclear pore complex (NPC) mediates all exchange between the cytoplasm and the nucleus. Small molecules can passively diffuse through the NPC, whereas larger cargos require transport receptors to translocate1. How the NPC facilitates the translocation of transport receptor/cargo complexes remains unclear. To investigate this process, we tracked single protein-functionalized quantum dot cargos as they moved through human NPCs. Here we show that import proceeds by successive substeps comprising cargo capture, filtering and translocation, and release into the nucleus. Most quantum dots are rejected at one of these steps and return to the cytoplasm, including very large cargos that abort at a size-selective barrier. Cargo movement in the central channel is subdiffusive and cargos that can bind more transport receptors diffuse more freely. Without Ran GTPase, a critical regulator of transport directionality1, cargos still explore the entire NPC, but have a markedly reduced probability of exit into the nucleus, suggesting that NPC entry and exit steps are not equivalent and that the pore is functionally asymmetric to importing cargos. The overall selectivity of the NPC seems to arise from the cumulative action of multiple reversible substeps and a final irreversible exit step.
Link
Абстракт статьи в Nature:
Selectivity mechanism of the nuclear pore complex characterized by single cargo tracking
Alan R. Lowe, Jake J. Siegel, Petr Kalab, Merek Siu, Karsten Weis & Jan T. Liphardt
Nature (2010) doi:10.1038/nature09285
Received 15 November 2009 Accepted 10 June 2010 Published online 01 September 2010
The nuclear pore complex (NPC) mediates all exchange between the cytoplasm and the nucleus. Small molecules can passively diffuse through the NPC, whereas larger cargos require transport receptors to translocate1. How the NPC facilitates the translocation of transport receptor/cargo complexes remains unclear. To investigate this process, we tracked single protein-functionalized quantum dot cargos as they moved through human NPCs. Here we show that import proceeds by successive substeps comprising cargo capture, filtering and translocation, and release into the nucleus. Most quantum dots are rejected at one of these steps and return to the cytoplasm, including very large cargos that abort at a size-selective barrier. Cargo movement in the central channel is subdiffusive and cargos that can bind more transport receptors diffuse more freely. Without Ran GTPase, a critical regulator of transport directionality1, cargos still explore the entire NPC, but have a markedly reduced probability of exit into the nucleus, suggesting that NPC entry and exit steps are not equivalent and that the pore is functionally asymmetric to importing cargos. The overall selectivity of the NPC seems to arise from the cumulative action of multiple reversible substeps and a final irreversible exit step.
Link
