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Single-molecule Super-resolution Imaging of Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane with Novel Fluorescent Probes
Published on: October 15, 2016
The PX domain as a novel phosphoinositide- binding module.
1Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
Biochemical and Biophysical Research Communications
|September 21, 2001
Summary
The phagocyte oxidase (phox) homology (PX) domain directly binds to phosphoinositides, acting as a novel membrane-targeting module. This discovery reveals the PX domain
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- The phox (phagocyte oxidase) homology (PX) domain is found in proteins regulating cellular processes.
- These proteins include mammalian p40(phox) and p47(phox), and yeast's Bem1p, involved in membrane trafficking and polarity establishment.
Purpose of the Study:
- To investigate the direct binding capabilities of PX domains to phosphoinositides.
- To elucidate the role of PX domains in protein localization to cellular membranes.
Main Methods:
- In vitro binding assays to test interactions between purified PX domains and various phosphoinositides.
- Expression of green fluorescent protein (GFP)-fused p40(phox) PX domain in HeLa cells to observe cellular localization.
- Analysis of a mutant p40(phox) PX domain with a specific amino acid substitution (Lys for Arg105) to assess binding and localization defects.
Main Results:
- PX domains of p40(phox) and p47(phox) directly bind to specific phosphoinositides: p40(phox) prefers PtdIns(3)P, while p47(phox) binds PtdIns(4)P and PtdIns(3,4)P(2).
- The Bem1p PX domain also interacts with PtdIns(4)P.
- In HeLa cells, the p40(phox) PX domain localizes to early endosomes, enriched in PtdIns(3)P.
- A mutant p40(phox) PX domain exhibited weak phosphoinositide binding in vitro and failed to localize to early endosomes.
Conclusions:
- The PX domain functions as a novel phosphoinositide-binding module.
- This binding activity is crucial for targeting proteins to specific membrane compartments, such as early endosomes.
- The findings suggest a general mechanism for membrane targeting mediated by PX domains in diverse cellular proteins.
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