Reverse cholesterol transport (RCT) is the process by which peripheral cell cholesterol is returned to the liver. The FIRST step of RCT involving HDL formation from lipid-poor apoA-I and membrane phospholipids requires:

• A CETP (Cholesterol ester transfer protein)
• B LCAT (Lecithin-cholesterol acyltransferase) converting free cholesterol to cholesterol esters
• C ABCA1 (ATP-binding cassette transporter A1) on peripheral cells effluxing cholesterol to apoA-I ✓
• D SR-B1 (scavenger receptor class B type 1) on hepatocytes

Explanation

Nascent HDL (discoidal, lipid-poor apoA-I) acquires cholesterol and phospholipids from peripheral cells via ABCA1. Tangier disease (ABCA1 loss-of-function) results in near-absent HDL and massive cholesterol deposition in reticuloendothelial cells. Subsequently, LCAT (activated by apoA-I) esterifies free cholesterol on HDL surface to cholesterol esters which migrate to the HDL core, forming mature spherical HDL. CETP transfers cholesterol esters to VLDL/LDL; SR-B1 on hepatocytes mediates the terminal selective cholesterol uptake from HDL.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.