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PI(4,5)P 2 Degradation Promotes the Formation of Cytoskeleton‐Free Model Membrane Systems
Author(s) -
Keller Heiko,
Lorizate Maier,
Schwille Petra
Publication year - 2009
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200900598
Subject(s) - membrane , chemistry , vesicle , biophysics , cytoskeleton , phosphatidylinositol , pi , biochemistry , cell , biology , signal transduction
Giant plasma membrane vesicles (GPMVs) are cell‐derived model membrane systems that undergo large‐scale lipid phase separation when cooled below room temperature. Because of their presumably more physiological lipid composition, they are increasingly used as alternatives to synthetic model membranes. However, the exact mechanism of GPMV formation, and thus, effects of this process on the physiological integrity of the membrane are still unclear. Herein, we identify the key steps of GPMV formation and characterize their differences with respect to the plasma membrane of intact cells. Addition of GPMV‐inducing reagents triggers a steady Ca 2+ influx that is accompanied by phosphatidylinositol 4,5‐bisphosphate [PI(4,5)P 2 ] degradation and phosphatidyl serine (PS) externalization before detachment of the cytoskeleton and the onset of vesicle formation. When comparing GPMVs to other cell‐derived model systems, PI(4,5)P 2 is not detectable in phase‐separating plasma membrane spheres (PMSs) either, but is present in non‐phase‐separating blebs. GPMVs differ from the physiological state of the plasma membrane in the presence of specific lipids, which limits their use as model systems. Furthermore, we propose that PI(4,5)P 2 influences the phase‐separation behavior.