Related Experiment Video
Updated: Oct 2, 2026

Using LEXY and LINuS Optogenetics Tools and Automated Image Analysis to Quantify Nucleocytoplasmic Transport Dynamics in Live Cells
Published on: July 22, 2025
Nuclear-localization-signal-dependent and nuclear-export-signal-dependent mechanisms determine the localization of
Hiromi Hanaka1, Takao Shimizu, Takashi Izumi
1Department of Biochemistry, Gunma University School of Medicine, 3-39-22 Showamachi, Maebashi, Gunma 371-8511, Japan.
Abstract:
5-Lipoxygenase (5-LO) metabolizes arachidonic acid to leukotriene A4, a key intermediate in leukotriene biosynthesis. To explore the molecular mechanisms of its cell-specific localization, a fusion protein between green fluorescent protein (GFP) and human 5-LO (GFP-5LO) was expressed in various cells. GFP-5LO was localized in the cytosol in HL-60 cells and in both the nucleus and the cytosol in RBL (rat basophilic leukaemia) cells, similarly to the native enzyme in these cells. The localization of GFP fusion proteins for mutant 5-LOs in a putative bipartite nuclear localization signal (NLS), amino acids 638-655, in Chinese hamster ovary (CHO)-K1 and Swiss3T3 cells revealed that this motif is important for the nuclear localization of 5-LO. A GFP fusion protein of this short peptide localized consistently in the nucleus. Leptomycin B, a specific inhibitor of nuclear export signal (NES)-dependent transport, diminished the cytosolic localization of 5-LO in HL-60 cells and that of GFP-5LO in CHO-K1 cells, suggesting that an NES-system might also function in determining 5-LO localization. Analysis of the localization of 5-LO during the cell cycle points to a controlled movement of this enzyme. Thus we conclude that a balance of NLS- and NES-dependent mechanisms determines the cell-type-specific localization of 5-LO, suggesting a nuclear function for this enzyme.
Related Concept Videos
Nuclear Localization Signals and Import
Regulation of Nuclear Protein Sorting
Nuclear Export
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
Nuclear Protein Sorting
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Regulated mRNA Transport
Directionality of Nuclear Transport

