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The Good, The Bad, and The Ugly: Charges and Their Role in Lipid Phase Separation
Recent literature has shown that buffers affect the interaction between lipid bilayers through a mechanism that involves van der Waals forces, electrostatics, hydration forces and membrane bending rigidity. This talk will highlight our recent work that shows phase coexistence can be a result of Goods buffer charges on the mixed chain 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid bilayers. Since the two phases must be in osmotic equilibrium with one another, this behavior challenges theoretical models of lipid interactions and introduces new variables to consider for the Gibbs phase rule. This model of lipid charging was then used to explain the mechanisms behind phase separation in lipid mixtures containing charged lipid head groups, particularly phosphatidylinositols. Furthermore, this work is then applied to our understanding of underlying mechanisms involved in membrane protein selective association with phosphoinositols, and later re-organization of these membranes.
This work was supported by NIH NCI K01-CA169078-01 and Indiana University Collaborative Research Grants.