What are intermediate-density lipoproteins (IDL)?

What are intermediate-density lipoproteins (IDL)?

• A. Transitional lipoproteins between VLDL and LDL in triglyceride metabolism
• B. Lipoproteins that transport cholesterol from liver to tissues
• C. Lipoproteins that remove cholesterol from tissues
• D. Lipoproteins that carry dietary cholesterol to liver

Answer: (A)

IDL are transitional lipoproteins formed during triglyceride metabolism when VLDL loses triglycerides via lipoprotein lipase. The resulting particle sits between VLDL and LDL, often called a VLDL remnant. It can be taken up by the liver via ApoE receptors or further processed by hepatic lipase to become LDL. This placement reflects its role in the pathway that moves lipids from liver-derived VLDL toward the cholesterol-delivering LDL, rather than transporting cholesterol to tissues (LDL does that), removing cholesterol from tissues (HDL does that), or carrying dietary cholesterol to the liver (that role is fulfilled by chylomicron remnants).

IDL are transitional lipoproteins formed during triglyceride metabolism when VLDL loses triglycerides via lipoprotein lipase. The resulting particle sits between VLDL and LDL, often called a VLDL remnant. It can be taken up by the liver via ApoE receptors or further processed by hepatic lipase to become LDL. This placement reflects its role in the pathway that moves lipids from liver-derived VLDL toward the cholesterol-delivering LDL, rather than transporting cholesterol to tissues (LDL does that), removing cholesterol from tissues (HDL does that), or carrying dietary cholesterol to the liver (that role is fulfilled by chylomicron remnants).