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Updated: Jun 3, 2026

Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes
Published on: October 15, 2016
Phosphoinositide binding by par-3 involved in par-3 localization.
Yosuke Horikoshi1, Sayaka Hamada, Shigeo Ohno
1Laboratory of Membrane and Cytoskeleton Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan.
Phosphoinositides bind to the par-3 protein at specific sites, influencing its cell junction localization. Mutations disrupting this binding weaken par-3
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Electrostatic interactions between lipids and proteins are crucial for cellular processes.
- Par-3 protein plays a role in cell-cell junction formation and maintenance.
Purpose of the Study:
- To investigate the interaction between phospholipids and the par-3 protein.
- To determine the role of phosphoinositide binding in par-3 localization at cell-cell junctions.
Main Methods:
- Identified phosphoinositide binding sites on par-3 using conserved basic residues.
- Utilized site-directed mutagenesis (K1013E/K1014E) to abolish lipid binding.
- Assessed protein localization and dynamics at cell-cell junctions using fluorescence microscopy and FRAP.
Main Results:
- Phosphatidylinositol phosphates (PIPs) bind to the C-terminal coiled-coil region of par-3.
- Lysine residues K1013 and K1014 form the phosphoinositide binding site.
- Mutating K1013/K1014 abolished PIP binding and significantly reduced par-3 localization and stability at cell-cell junctions.
- Inhibition of phosphatidylinositol 3-kinases partially increased par-3 turnover.
Conclusions:
- The binding of phosphoinositides to par-3 is essential for its proper localization and stability at cell-cell junctions.
- This interaction highlights a novel regulatory mechanism for par-3 function in cell adhesion.
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