title: Fluorescent recovery after photobleaching (FRAP) analysis of nuclear export rates identifies intrinsic features of nucleocytoplasmic transport.
abstract: A quantitative description of carrier-mediated nuclear export in live cells is presented. To this end, we fused a prototypical leucine-rich nuclear export signal (NES) to GFP as a cargo model and expressed the fluorescent chimera in live CHO-K1 cells. By modeling FRAP data, we calculate the NES affinity for the export machinery and the maximum rate of nuclear export achievable at saturation of endogenous carriers. The measured active-export time through the Nuclear Pore Complex (NPC) is 18 ms, remarkably similar to the previously determined active-import rate. Also, our results reveal that active export/import and active export/passive diffusion fluxes are uncoupled, thus complementing previous reports on active import/passive diffusion uncoupling. These findings suggest differential gating at the NPC level.
authors.affiliation: Center for Nanotechnology Innovation @ NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12-56127 Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Cardarelli
authors.forename: Luca
authors.initials: L
authors.lastname: Tosti
authors.forename: Michela
authors.initials: M
authors.lastname: Serresi
authors.forename: Fabio
authors.initials: F
authors.lastname: Beltram
authors.forename: Ranieri
authors.initials: R
authors.lastname: Bizzarri
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D016466:CHO Cells; D002467:Cell Nucleus / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D004058:Diffusion; D036681:Fluorescence Recovery After Photobleaching; D007700:Kinetics; D008954:Models, Biological; D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals; D022022:Nuclear Pore / Q000378:metabolism; D013816:Thermodynamics
chemical_list: D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals