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Updated: Dec 13, 2025

Fluorescence-Based Measurements of Phosphatidylserine/Phosphatidylinositol 4-Phosphate Exchange Between Membranes
Published on: March 14, 2021
A complex genetic interaction implicates that phospholipid asymmetry and phosphate homeostasis regulate Golgi
Mamoru Miyasaka1,2, Tetsuo Mioka1, Takuma Kishimoto1
1Division of Molecular Interaction, Institute for Genetic Medicine, Hokkaido University Graduate School of Life Science, Sapporo, Hokkaido, Japan.
This study reveals that luminal phosphate concentration, not just phospholipid flippases, is crucial for maintaining Golgi membrane function and phospholipid asymmetry in yeast cells. Disruptions in phosphate transport impact membrane trafficking and cellular stress responses.
Area of Science:
- Cell Biology
- Membrane Biology
- Biochemistry
Background:
- Phospholipid flippases regulate lipid bilayer asymmetry in eukaryotic cells.
- Cdc50p-Drs2p and Neo1p are key flippases in yeast Golgi and endosomal trafficking.
- The role of Cfs1p in phospholipid asymmetry was previously unknown.
Purpose of the Study:
- Investigate the function of Cfs1p in relation to phospholipid asymmetry.
- Identify genes functionally relevant to NEO1 and CFS1.
- Elucidate the coordinated regulation of Golgi membrane functions.
Main Methods:
- Genetic analysis of yeast mutants (neo1Δ, cdc50Δ, cfs1Δ, erd1Δ).
- Observation of membrane trafficking and protein localization.
- Analysis of endoplasmic reticulum (ER) structure and unfolded protein response.
Main Results:
- The ERD1 gene was identified as synthetically lethal with neo1Δ cfs1Δ.
- Neo1p-depleted cfs1Δ erd1Δ mutants showed Golgi accumulation of plasma membrane proteins and ER abnormalities.
- Accumulation of inorganic phosphate (Pi) in the Golgi lumen was linked to Golgi dysfunction.
Conclusions:
- Luminal ionic environment, specifically Pi concentration, is functionally relevant to phospholipid asymmetry.
- Flippase activity and luminal Pi concentration coordinately regulate Golgi membrane functions.
- Cfs1p and Erd1p play roles in maintaining phospholipid asymmetry and Golgi homeostasis.
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