Lipid metabolism and regulation of membrane trafficking

The past 20 years have witnessed tremendous progress in our understanding o f the molecular machinery that controls protein and membrane transport betw een organelles (Scheckman R. Orci L. Coat proteins and vesicle budding. Sci ence 1996;271: 1526-1533 and Rothman JE. Mechanisms of intracellular protei n transport. Nature 1994;372: 55-63.) The research efforts responsible for these impressive advances have largely focused on the identification and ch aracterization of protein factors that participate in membrane trafficking events. The role of membranes and their lipid constituents has received con siderably less attention. Indeed, until rather recently, popular models for mechanisms of membrane trafficking had relegated membrane lipids to the st atus of a passive platform, subject to deformation by the action of coat pr oteins whose polymerization and depolymerization govern vesicle budding and fusion reactions. The 1990s, and particularly its last half, has brought f undamental reappraisals of the interface of lipids and lipid metabolism in regulating intracellular membrane trafficking events. Some of the emerging themes are reviewed here.