Which one of the following is common for chylomicron and VLDL?
a. Both have B48 and C-II
b. Both are produced by the liver
c. Both can be used by lipoprotein lipase
d. Both degraded in hepatic tissue
The correct answer and explanation is:
The correct answer is c. Both can be used by lipoprotein lipase.
Explanation:
Chylomicrons and Very Low-Density Lipoproteins (VLDL) are both lipoproteins involved in the transport of lipids (fats) in the body, but they have distinct origins, structures, and functions. However, a shared feature between the two is their interaction with lipoprotein lipase (LPL).
- Lipoprotein Lipase (LPL) Activation:
Both chylomicrons and VLDL particles contain apolipoproteins that are crucial for their recognition and breakdown by lipoprotein lipase. The enzyme LPL is located on the endothelial cells of capillaries, especially in adipose tissue, muscle tissue, and the heart. LPL catalyzes the hydrolysis of triglycerides from these lipoproteins, releasing free fatty acids, which can then be taken up by tissues for energy or storage. - Chylomicrons:
Chylomicrons are formed in the intestines after the digestion of dietary fats. They are primarily composed of triglycerides and contain apolipoprotein B-48 (ApoB-48) as a structural protein. Chylomicrons enter the bloodstream via the lymphatic system and transport dietary triglycerides to various tissues. After triglycerides are removed by LPL, chylomicron remnants, which contain cholesterol and phospholipids, are cleared by the liver. - VLDL:
VLDL is synthesized primarily in the liver and is responsible for transporting endogenously synthesized triglycerides from the liver to peripheral tissues. VLDL contains apolipoprotein B-100 (ApoB-100) and also has ApoC-II, which activates LPL. Like chylomicrons, VLDL undergoes hydrolysis by LPL to release free fatty acids, and the remnants are converted into low-density lipoproteins (LDL) as they lose triglycerides. - Conclusion:
Both chylomicrons and VLDL interact with lipoprotein lipase for triglyceride hydrolysis, a key step in lipid metabolism. While they have different origins (intestinal vs. hepatic) and apolipoproteins (ApoB-48 vs. ApoB-100), they share this functional characteristic. Therefore, the correct answer is that both chylomicrons and VLDL can be used by lipoprotein lipase.