A 45-year-old man with type 2 diabetes has elevated triglycerides and reduced HDL. Lipoprotein lipase activity on chylomicrons and VLDL is decreased due to insulin deficiency. The apolipoprotein that functions as the obligate activator of lipoprotein lipase (LPL) on chylomicrons is:
- A Apo B-48
- B Apo C-II ✓
- C Apo E
- D Apo A-I
Correct answer: B. Apo C-II
Explanation
Apolipoprotein C-II is the essential cofactor (activator) for lipoprotein lipase, which hydrolyses triglycerides in chylomicrons and VLDL at capillary surfaces of adipose and muscle. Apo C-II is transferred from HDL to nascent chylomicrons and VLDL, making HDL a donor of activating apoprotein. Deficiency of apo C-II causes familial hyperchylomicronemia (type I hyperlipoproteinemia) clinically identical to LPL deficiency. Apo B-48 is structural to chylomicrons; Apo E mediates remnant receptor uptake; Apo A-I activates LCAT on HDL.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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