Lipid phase fatty acid flip-flop, is it fast enough for cellular transport?

The mechanism by which fatty acids are transported across cell membranes is controversial. The essence of the controversy is whether transport require s membrane protein mediation or whether the membrane's lipid phase provides a pathway so rapid that a protein is not needed, This review focuses on th e mechanisms of fatty acid transport across lipid bilayer membranes. These results for lipid membranes are used to help evaluate transport across cell membranes. Within the context of this analysis, a lipid phase mediated pro cess is consistent with results for the transport of fatty acids across ery throcytes but provides a less adequate explanation for fatty acid transport across more complex cells.