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.