EXPRESSION OF LIVER FATTY-ACID-BINDING PROTEIN IN L-CELLS - PLASMA-MEMBRANE RESPONSE TO ETHANOL

Expression of liver fatty acid binding protein (L-FABP) in transfected L-cell fibroblasts modifies plasma membrane structure and function [I ncerpi et al., 1992, Arch. Biochem, Biophys, 298, 35-42], The effect o f L-FABP expression on ethanol induced fluidization of plasma membrane s was examined. Ethanol in vitro selectively fluidized the exofacial l eaflet of the plasma membranes from L-cells expressing low amounts of L-FABP, In contrast, the plasma membranes from L-cells expressing high amounts of L-FABP were resistant to the actions of ethanol. Furthermo re, diphenylhexatriene lifetime distributional analysis demonstrated t hat the plasma membrane exofacial leaflet had a lower range of apparen t dielectric constants than the cytofacial leaflet for both low- and h igh-expression cells. Both the center of lifetime and the lifetime dis tributional width of diphenylhexatriene in the bulk plasma membrane ve rsus the cytofacial leaflet were consistent with significantly lower a pparent dielectric constant in the exofacial leaflet of high-expressio n versus low-expression cells. Ethanol in vitro preferentially increas ed the exofacial leaflet apparent dielectric properties of the plasma membranes from low-expression but not high-expression cells. In conclu sion, ethanol appears to dehydrate the lipid headgroups of plasma memb ranes from high-expression cells, thereby conferring resistance to eth anol fluidization. In contrast, ethanol may not dehydrate the plasma m embrane lipid head groups of low-expression cells, resulting in ethano l fluidizing the outer leaflet of the plasma membrane. (C) 1995 Academ ic Press, Inc.