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Permeability of single nuclear pores
1Institut für Medizinische Physik und Biophysik, Universität Münster, D-48149 Münster, Germany.
Biophysical Journal
|July 2, 1999
Summary
Optical single transporter recording (OSTR) measured nuclear pore complex (NPC) passive permeability. The NPC acts as a single diffusion channel, approximately 5.35 nm in radius and 44.5 nm long, limiting dextran passage to <40 kDa.
Area of Science:
- Cell Biology
- Biophysics
Background:
- The nuclear pore complex (NPC) regulates transport between the nucleus and cytoplasm.
- Understanding NPC passive permeability is crucial for comprehending molecular transport dynamics.
Purpose of the Study:
- To measure the passive permeability of the NPC using optical single transporter recording (OSTR).
- To characterize the physical dimensions of the NPC's transport channel.
Main Methods:
- Isolated Xenopus oocyte nuclei were used.
- Optical single transporter recording (OSTR) and scanning microphotolysis were employed to measure transport.
- Fluorescently labeled dextrans of varying sizes (4, 10, 20, and >=40 kDa) were used as probe molecules.
Main Results:
- The NPC demonstrated passive permeability to dextrans up to 20 kDa, with >/=40 kDa dextrans unable to permeate.
- Data supported a model of the NPC containing a single diffusion channel.
- The diffusion channel was approximated as a cylinder with a radius of 4.4-6.1 nm (mean 5.35 nm) and a length of 40-50 nm (mean 44.5 nm).
Conclusions:
- The NPC functions with a central, singular diffusion channel mediating passive transport.
- This suggests a common pathway for both passive and signal-dependent transport through the NPC.
- Further studies are planned to investigate signal-dependent transport and its interplay with passive transport.