Participation of sterol carrier protein-2 in cholesterol metabolism.

818 Introduction Lipid transport between intracellular organelles is thought to involve carrier proteins. Several different lipid transfer proteins have been isolated which are involved in the transport of phosphatidylcholine, phosphatidylinositol, phosphatidylserine, cholesterol, gangliosides, glycolipids, dolichol and vitamin D3 [ 1-31. In addition to protein mediated transport, other processes, such as diffusion at membrane contact sites and spontaneous transfer between membranes, are thought to occur [l-51. This review primarily deals with steroVcholesterol transport proteins in mammalian cells. In spite of the tremendous amount of information available regarding extracellular cholesterol transport, there is a paucity of information with regard to intracellular cholesterol transport. In this review, we present evidence relating to transport, utilization and synthesis of cholesterol via the participation of one such intracellular transport protein, namely sterol carrier protein-2 (SCP-2). We hope that this review will stimulate further study in a field that has shown considerable progress in the last few years.