Which transporter mediates the efflux of cholesterol from peripheral cells into HDL?

Which transporter mediates the efflux of cholesterol from peripheral cells into HDL?

• A. CETP
• B. High density lipoprotein
• C. Apolipoprotein B
• D. ATP-binding cassette transporter A1

Answer: (D)

Cholesterol efflux from peripheral cells into HDL is driven by ABCA1, an ATP-binding cassette transporter that moves cholesterol and phospholipids to lipid-poor apolipoprotein A-I, forming nascent HDL particles and kicking off reverse cholesterol transport. This energy-dependent process explains why ABCA1 is the best answer. CETP is involved in exchanging cholesteryl esters from HDL for triglycerides with other lipoproteins, not in the initial efflux step. Apolipoprotein B is the main protein of VLDL/LDL and does not mediate cellular cholesterol efflux. HDL serves as the acceptor particle, but the actual transporter moving cholesterol out of cells is ABCA1. Defects in ABCA1 lead to very low HDL levels and tissue cholesterol accumulation (Tangier disease), illustrating the transporter’s role.

Cholesterol efflux from peripheral cells into HDL is driven by ABCA1, an ATP-binding cassette transporter that moves cholesterol and phospholipids to lipid-poor apolipoprotein A-I, forming nascent HDL particles and kicking off reverse cholesterol transport. This energy-dependent process explains why ABCA1 is the best answer. CETP is involved in exchanging cholesteryl esters from HDL for triglycerides with other lipoproteins, not in the initial efflux step. Apolipoprotein B is the main protein of VLDL/LDL and does not mediate cellular cholesterol efflux. HDL serves as the acceptor particle, but the actual transporter moving cholesterol out of cells is ABCA1. Defects in ABCA1 lead to very low HDL levels and tissue cholesterol accumulation (Tangier disease), illustrating the transporter’s role.