Ядро раст клетки‎ > ‎pcp131‎ > ‎
http://www.nature.com/nature/journal/vaop/ncurrent/abs/nature09285.html 27/9/10
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
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.
These authors contributed equally to this work.
Alan R. Lowe &
Jake J. Siegel
Department of Physics, University of California, Berkeley, California 94720, USA
Jan T. Liphardt
QB3, University of California, Berkeley, California 94720, USA
Karsten Weis &
Bay Area Physical Sciences–Oncology Center, University of California, Berkeley, California 94720, USA
Biophysics Graduate Group, University of California, Berkeley, California 94720, USA
Merek Siu &
Department of Molecular and Cellular Biology, University of California, Berkeley, California 94720, USA
Petr Kalab &
Physical Biosciences Division, Lawrence Berkeley National Laboratory, California 94720, USA
Present addresses: Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892, USA (P.K.); Illumina Inc., Hayward, California 94545, USA (M.S.).
Merek Siu
A.R.L., J.J.S., P.K., M.S., K.W. and J.T.L. designed the experiments. A.R.L., J.J.S. and P.K. prepared materials. A.R.L. and J.J.S. performed the QD optimization and functionalization, the single-molecule experiments, and the data analysis. A.R.L., J.J.S., K.W. and J.T.L. wrote the manuscript.
Competing financial interests
Karsten Weis (kweis@berkeley.edu)
Supplementary Movie 1 (24.4M)
A typical movie showing imported QDs in a single nucleus after 20 minutes of import. 2 QDs are seen to diffuse inside the confined volume of the cell nucleus. The fitted outline of the nuclear envelope taken from a brightfield image taken immediately after this movie is overlaid in green.
Supplementary Movie 2 (691K)
An example of single QD cargo successfully translocating through a NPC. The nuclear envelope bisects the field of view, running from top to bottom. The QD is observed arriving from the cytoplasm (left), residing at the NPC, and then leaving into the nucleus (right).
Supplementary Information (4.4M)
This file contains Supplementary Information 1-8, Supplementary Figures 1-13 with legends, Supplementary Tables 1-3 and additional references.
This is a public forum. Please keep to our Community Guidelines. You can be controversial, but please don't get personal or offensive and do keep it brief. Remember our threads are for feedback and discussion - not for publishing papers, press releases or advertisements. If you find something abusive or inappropriate or which does not otherwise comply with our Terms orCommunity Guidelines, please select the relevant 'Report this comment' link.
You need to be registered with Nature and agree to our Community Guidelines to leave a comment. Please log in or register as a new user. You will be re-directed back to this page.