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Updated: Jun 30, 2026

Single-Molecule Imaging of Nuclear Transport
Published on: June 9, 2010
Autonomy and robustness of translocation through the nuclear pore complex: a single-molecule study
Thomas Dange1, David Grünwald, Antje Grünwald
1Institute for Physical and Theoretical Chemistry, Rheinische Friedrich-Wilhelms-University Bonn, D-53115 Bonn, Germany.
Abstract:
All molecular traffic between nucleus and cytoplasm occurs via the nuclear pore complex (NPC) within the nuclear envelope. In this study we analyzed the interactions of the nuclear transport receptors kapalpha2, kapbeta1, kapbeta1DeltaN44, and kapbeta2, and the model transport substrate, BSA-NLS, with NPCs to determine binding sites and kinetics using single-molecule microscopy in living cells. Recombinant transport receptors and BSA-NLS were fluorescently labeled by AlexaFluor 488, and microinjected into the cytoplasm of living HeLa cells expressing POM121-GFP as a nuclear pore marker. After bleaching the dominant GFP fluorescence the interactions of the microinjected molecules could be studied using video microscopy with a time resolution of 5 ms, achieving a colocalization precision of 30 nm. These measurements allowed defining the interaction sites with the NPCs with an unprecedented precision, and the comparison of the interaction kinetics with previous in vitro measurements revealed new insights into the translocation mechanism.
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