Phosphatidylinositol-4-Phosphate Domain Properties in Asymmetric Giant Unilamellar Vesicles

Reynolds, Catherine

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Phosphatidylinositol-4-Phosphate Domain Properties in Asymmetric Giant Unilamellar Vesicles

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Phosphatidylinositol-4-phosphate (PI(4)P) is a precursor for higher phosphorylated phosphoinositide species and directly mediates many cellular processes at the plasma membrane and in the Golgi. Cellular membranes are vertically asymmetric and, with respect to lipid distribution, laterally heterogenous. It has been hypothesized that many physiological functions affected by PI(4)P are associated with clustering of the lipid. At present, it is unclear to what extent clustering of PI(4)P is present in asymmetric lipid bilayers. Asymmetric giant unilamellar vesicles (aGUVs) are model systems that allow for the visualization of lipid interactions within a phospholipid bilayer using confocal fluorescence microscopy. Novel techniques have only recently enabled the fabrication of aGUVs. We are using the hemifusion method to obtain aGUVs with PI(4)P containing lipid mixtures in one leaflet and DOPC in the opposing leaflet. As a first step towards studying PI(4)P clustering in asymmetric vesicles, we report here on the conditions required for the formation of PI(4)P-containing aGUVs. Our experiments are designed to determine the conditions under which PI(4)P domain formation is favored and ultimately plan to investigate the registration of PIP domains with raft domains in the opposite leaflet.

This report represents the work of one or more WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review.

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