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#phospholipid transport

3 public questions tagged with this topic.

Which enzyme is responsible for maintaining lipid asymmetry by moving phospholipids to the inner leaflet?

Enzymatic control of transbilayer phospholipid distribution involves three distinct activities defined directionally. Flippase originally term for inward moving ATP dependent P4-ATPases ATP8A1 present in liver canaliculi ATP8B1 deficient in familial intrahepatic cholestasis, ATP11C required lymphocyte development, translocate aminophospholipids phosphatidylserine and phosphatidylethanolamine from exoplasmic to cytosolic leaflet maintaining negative inner surface important for vesicle formation and apoptosis prevention. Floppase ABC transporters ABCB1 multidrug resistance P-glycoprotein ABCB4 p

Ref: Pomorski et al., Lipid Transport by P4-ATPase Flippases, J Lipid Res Review.

Which ABC transporter plays a role in cholesterol and phospholipid transport in hepatocytes?

Row labeled Q30 appears truncated but query addresses which ABC transporter handles cholesterol and phospholipid transport in hepatocytes. In canalicular membrane ABCB4 MDR3 is established phosphatidylcholine floppase essential for biliary phospholipid secretion, pairing with bile salt export via ABCB11 and cholesterol export via ABCG5/G8. Its ATP-driven flipping of phosphatidylcholine to outer leaflet allows bile acids to extract lipid into mixed micelles that solubilize cholesterol and buffer bile acid detergent toxicity. At sinusoidal membrane, ABCA1 effluxes cholesterol and phospholipid to

Ref: Borst et al., Annu Rev Biochem 2000, ABC transporters in lipid transport; Alberts, Chapter 11.

Which ABC transporter plays a role in cholesterol and phospholipid transport in hepatocytes?

Cholesterol and phospholipid homeostasis in hepatocytes involves coordinated action of several ABC transporters at canalicular membrane. ABCB4 MDR3 flips phosphatidylcholine from inner to outer leaflet making it available for bile salt extraction forming mixed micelles that protect biliary epithelium and solubilize cholesterol exported by ABCG5/G8 heterodimer. ABCB1 MDR1 primarily exports hydrophobic xenobiotics and drugs, not bulk phospholipid for bile formation, though it can translocate short-chain lipids in vitro. ABCA1, not listed among options but relevant, mediates phospholipid and chol

Ref: Oude Elferink & Paulusma 2007, Hepatic lipid transporters; Nicolaou et al., J Hepatol 2012.