ApoB-100

Definition

apoB-100 is a large protein that is the primary apolipoprotein found in low-density lipoproteins (LDLs). It is essential for the assembly and secretion of very low-density lipoproteins (VLDLs) from the liver and the subsequent conversion of VLDLs into LDLs.

5 Must Know Facts For Your Next Test

1. apoB-100 is the sole structural protein component of LDL, and is essential for the formation and secretion of VLDL from the liver.
2. The binding of apoB-100 to the LDL receptor is the primary mechanism by which LDL cholesterol is taken up by cells.
3. Elevated levels of apoB-100 are associated with an increased risk of developing cardiovascular disease, as it can lead to the buildup of cholesterol in the arteries.
4. Genetic disorders that affect the production or function of apoB-100 can result in familial hypercholesterolemia, a condition characterized by high levels of LDL cholesterol.
5. Measurement of apoB-100 levels can provide a more accurate assessment of cardiovascular disease risk than traditional lipid panels, which only measure total cholesterol and LDL cholesterol.

Review Questions

• Explain the role of apoB-100 in the assembly and secretion of very low-density lipoproteins (VLDLs) from the liver.
  • apoB-100 is the essential structural protein component of VLDLs, and is required for their assembly and secretion from the liver. Without apoB-100, the liver would be unable to package and export triglycerides and other lipids as VLDLs, which are then converted to LDLs and transported throughout the body. The binding of apoB-100 to the necessary lipids and enzymes is a crucial step in the VLDL formation process, highlighting its central role in lipoprotein metabolism.
• Describe the relationship between elevated levels of apoB-100 and the development of cardiovascular disease.
  • Increased levels of apoB-100 are strongly associated with an increased risk of developing cardiovascular disease. This is because apoB-100 is the primary apolipoprotein found in LDL, the 'bad' cholesterol. Higher levels of apoB-100 mean more LDL particles are present in the bloodstream, leading to a greater potential for cholesterol buildup and plaque formation in the arteries. This atherosclerotic process can eventually restrict blood flow and increase the risk of heart attacks and strokes. Monitoring and controlling apoB-100 levels is therefore an important strategy for reducing cardiovascular disease risk.
• Analyze how genetic disorders affecting apoB-100 production or function can lead to familial hypercholesterolemia.
  • Genetic mutations that disrupt the normal production or function of apoB-100 can result in familial hypercholesterolemia, a condition characterized by extremely high levels of LDL cholesterol. If the liver is unable to properly assemble and secrete VLDLs due to apoB-100 defects, the clearance of LDL particles from the bloodstream is impaired. This causes a buildup of LDL cholesterol, which can then accumulate in the arteries and lead to premature development of cardiovascular disease. Understanding the central role of apoB-100 in lipoprotein metabolism provides insight into the genetic basis of familial hypercholesterolemia and the importance of maintaining healthy apoB-100 levels.

Related terms

Apolipoprotein: Apolipoproteins are proteins that bind to lipids to form lipoproteins, which transport lipids through the bloodstream.

Low-Density Lipoprotein (LDL): LDL is a type of lipoprotein that transports cholesterol from the liver to the body's cells, and is often referred to as 'bad' cholesterol.

Very Low-Density Lipoprotein (VLDL): VLDL is a type of lipoprotein that transports triglycerides from the liver to the body's cells, and can be converted to LDL.