title: Passive permeability and effective pore size of HeLa cell nuclear membranes.
abstract: Nuclear pore complexes in the nuclear membrane act as the sole gateway of transport of molecules from the cytoplasm to the nucleus and vice versa. Studies on biomolecular transport through nuclear membranes provide vital data on the nuclear pore complexes. In this work, we use fluorescein isothiocyanate-labeled dextran molecules as a model system and study the passive nuclear import of biomolecules through nuclear pore complexes in digitonin-permeabilized HeLa cells. Experiments are carried out under transient conditions in the time lapse imaging scheme using an in-house constructed confocal laser scanning microscope. Transport rates of dextran molecules having molecular weights of 4-70 kDa corresponding to Stokes radius of 1.4-6 nm are determined. Analyzing the permeability of the nuclear membrane for different sizes the effective pore radius of HeLa cell nuclear membrane is determined to be 5.3 nm, much larger than the value reported earlier using proteins as probe molecules. The range of values reported for the nuclear pore radius suggest that they may not be rigid structures and it is quite probable that the effective pore size of nuclear pore complexes is critically dependent on the probe molecules and on the environmental factors.
authors.affiliation: Department of Physics, Birla Institute of Technology and Science, Pilani-KK Birla Goa Campus, Zuari Nagar, 403 726, Goa, India.|Department of Biological Sciences, Birla Institute of Technology and Science, Pilani-KK Birla Goa Campus, Zuari Nagar, 403 726, Goa, India.
authors.forename: Arunkarthick
authors.initials: A
authors.lastname: Samudram
authors.affiliation: Department of Physics, Birla Institute of Technology and Science, Pilani-KK Birla Goa Campus, Zuari Nagar, 403 726, Goa, India.
authors.forename: Bijeesh M
authors.initials: BM
authors.lastname: Mangalassery
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science, Pilani-KK Birla Goa Campus, Zuari Nagar, 403 726, Goa, India.
authors.forename: Meenal
authors.initials: M
authors.lastname: Kowshik
authors.affiliation: Department of Physics, Birla Institute of Technology and Science, Pilani-KK Birla Goa Campus, Zuari Nagar, 403 726, Goa, India.
authors.forename: Nandakumar
authors.initials: N
authors.lastname: Patincharath
authors.affiliation: Department of Physics, Birla Institute of Technology and Science, Pilani-KK Birla Goa Campus, Zuari Nagar, 403 726, Goa, India.
authors.forename: Geetha K
authors.initials: GK
authors.lastname: Varier
mesh_terms: D021581:Active Transport, Cell Nucleus; D002463:Cell Membrane Permeability; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D018613:Microscopy, Confocal; D009685:Nuclear Envelope / Q000378:metabolism; D022022:Nuclear Pore / Q000378:metabolism*; D010539:Permeability; D059008:Time-Lapse Imaging
keywords: FITC-labeled dextran; confocal imaging; diffusion through membranes; nuclear membranes; nuclear pore complex; nuclear transport