Apoproteins, CM, VLDL

Question 1

What are apolipoproteins?

Answer 1

Protein components of lipoproteins that stabilize structure and mediate metabolism (e.g., Apo B-100, Apo A-I).

Question 2

List key apolipoproteins and their functions.

Answer 2

Apo B-100: LDL receptor binding. Apo A-I: HDL structure/LCAT activation. Apo C-II: LPL cofactor. Apo E: Remnant uptake.

Question 3

What is the overview of lipoprotein metabolism?

Answer 3

1) Chylomicrons transport dietary lipids. 2) VLDL transports hepatic lipids. 3) LPL converts them to remnants. 4) HDL mediates reverse transport.

Question 4

How does VLDL convert to LDL?

Answer 4

1) LPL removes TGs from VLDL → IDL. 2) Hepatic lipase further processes IDL → LDL (cholesterol-rich).

Question 5

What is CETP’s role in metabolism?

Answer 5

Cholesteryl ester transfer protein exchanges TGs from VLDL with cholesterol esters from HDL (linking their metabolism).

Question 6

Which apolipoprotein is defective in familial hyperchylomicronemia?

Answer 6

Apo C-II deficiency → LPL cannot breakdown chylomicrons → milky plasma.

Question 7

What recognizes Apo E on lipoprotein remnants?

Answer 7

Liver receptors (LRP and Apo E receptors) clear chylomicron/VLDL remnants.

Question 8

How does HDL participate in reverse cholesterol transport?

Answer 8

1) Collects cholesterol via ABCA1. 2) LCAT esterifies it. 3) CETP transfers esters to LDL for liver uptake.

Question 9

What happens when CETP is inhibited?

Answer 9

Increased HDL-C and decreased LDL-C (pharmacologic target in dyslipidemia).

Question 10

Which apolipoprotein is exclusively in chylomicrons?

Answer 10

Apo B-48 (intestinal form, truncated version of Apo B-100).