Related Experiment Video
Updated: Aug 3, 2025

Cholesterol Efflux Assay
Published on: March 6, 2012
Tom40 in cholesterol transport
Himangshu S Bose1,2, Mahuya Bose3, Randy M Whittal4
1Laboratory of Biochemistry and Cell Biology, Department of Biomedical Sciences, Mercer University School of Medicine, Savannah, GA 31404, USA.
Abstract:
Cholesterol initiates steroid metabolism in adrenal and gonadal mitochondria, which is essential for all mammalian survival. During stress an increased cholesterol transport rapidly increases steroidogenesis; however, the mechanism of mitochondrial cholesterol transport is unknown. Using rat testicular tissue and mouse Leydig (MA-10) cells, we report for the first time that mitochondrial translocase of outer mitochondrial membrane (OMM), Tom40, is central in cholesterol transport. Cytoplasmic cholesterol-lipids complex containing StAR protein move from the mitochondria-associated ER membrane (MAM) to the OMM, increasing cholesterol load. Tom40 interacts with StAR at the OMM increasing cholesterol transport into mitochondria. An absence of Tom40 disassembles complex formation and inhibits mitochondrial cholesterol transport and steroidogenesis. Therefore, Tom40 is essential for rapid mitochondrial cholesterol transport to initiate, maintain, and regulate activity.
Related Concept Videos
Cholesterol: Significance and Regulation
Considering cholesterol and...
Carrier-Mediated Transport
Active transport involves two types of membrane-spanning transporters: uptake and efflux. Uptake transporters are expressed in the small...
Lipid Absorption
These breakdown products bind with bile salts and lecithin to form micelles, which quickly pass between microvilli to come in close contact with the apical...
Membrane Asymmetry Regulating Transporters
Flippase
Eukaryotic flippases are type-IV P-type ATPases or P4-ATPases belonging to P-type ATPase family proteins that are membrane-bound pumps involved in the ATP-mediated transport of ions and molecules across the membrane. Flippases flip specific phospholipids from the outer to the inner leaflet of a membrane. All P4-ATPases have one...
Cellular Membranes and Drug Transport
Phospholipids arrange themselves into a bilayer, with hydrophilic heads oriented outward and hydrophobic tails facing inward.
Hepatic Drug Clearance: Role of Transporters

