Intracellular cholesterol transport

Cholesterol can be transported among organelles by both vesicular and non‐vesicular transport. We have used well‐behaved fluorescent sterols, including dehydroergosterol (DHE), to study sterol transport in a variety of mammalian cells. In CHO cells, we have found that approximately one million sterol molecules per second are exchanged between the plasma membrane and the endocytic recycling compartment, mainly by non‐vesicular transport. Other studies have documented non‐vesicular transport between the plasma membrane and the endoplasmic reticulum. We have found that StarD4, a small cytoplasmic cholesterol‐binding protein, can rapidly exchange sterol between liposomes, and in cells it can regulate sterol transport to the endoplasmic reticulum. The role of sterol transport on StarD4 in cholesterol homeostasis in cells will be discussed.