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Phospholipase C-delta1 contains a functional nuclear export signal sequence.
1Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Garden City, Hyogo 678-1297, Japan.
The Journal of Biological Chemistry
|September 25, 1999
Summary
Phospholipase C-delta 1 (PLC-delta1) is actively transported between the cytoplasm and nucleus. A specific nuclear export signal (NES) directs its export, while nuclear import signals remain unidentified.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Previous studies indicated Phospholipase C-delta 1 (PLC-delta1) primarily localizes to the plasma membrane and cytosol.
- Limited nuclear presence of PLC-delta1 was observed in Madin-Darby canine kidney cells.
Purpose of the Study:
- To investigate the nuclear localization and transport mechanisms of PLC-delta1.
- To identify functional signals regulating PLC-delta1's subcellular localization.
Main Methods:
- Utilized a green fluorescent protein (GFP) fusion system to track PLC-delta1 localization.
- Disrupted the identified nuclear export signal (NES) in GFP/PLC-delta1 constructs.
- Treated cells with leptomycin B, a specific inhibitor of NES-dependent nuclear export.
- Examined localization of a site-directed mutant with a non-functional pleckstrin homology (PH) domain.
Main Results:
- A functional NES was identified in amino acid residues 164-177 of the EF-hand domain of PLC-delta1.
- Disruption of the NES led to increased nuclear presence of GFP/PLC-delta1.
- Leptomycin B treatment caused GFP/PLC-delta1 accumulation in the nucleus.
- A PH domain mutant showed greater nuclear accumulation than wild-type PLC-delta1 upon leptomycin B treatment.
Conclusions:
- PLC-delta1 undergoes active nucleocytoplasmic shuttling.
- Nuclear export of PLC-delta1 is mediated by a leucine-rich NES sequence.
- The regulation of active nuclear import of PLC-delta1 involves as yet unidentified signals.