Ch. 18: Lipids III: Plasma Lipoproteins Flashcards Preview

Medical Biochemistry > Ch. 18: Lipids III: Plasma Lipoproteins > Flashcards

Flashcards in Ch. 18: Lipids III: Plasma Lipoproteins Deck (25):
1

Apoliproteins: ApoA-I

Associated lipoprotein?
Function/characteristics?

HDL

Activates lecithin:cholesterol acyltransferase (LCAT)

2

Apoliproteins: ApoB-48

Associated lipoprotein?
Function/characteristics?

Chylomicrons

Derived from apoB-100 gene via RNA editing in intestinal epithelium
Lacks LDL receptor-binding domain of apoB-100

3

Apoliproteins: ApoB-100

Associated lipoprotein?
Function/characteristics?

VLDL, IDL, LDL

Binds to LDL receptor

4

Apoliproteins: ApoC-I

Associated lipoprotein?
Function/characteristics?

Chylomicrons, VLDL, IDL, HDL

May also activate lecithin:cholesterol acyltransferase (LCAT)

5

Apoliproteins: ApoC-II

Associated lipoprotein?
Function/characteristics?

Chylomicrons, VLDL, IDL, HDL

Activates lipoprotein lipase (LPL)

6

Apoliproteins: ApoC-III

Associated lipoprotein?
Function/characteristics?

Chylomicrons, VLDL, IDL, HDL

inhibits lipoprotein lipase (LPL)

7

Apoliproteins: ApoD

Associated lipoprotein?
Function/characteristics?

HDL

Associated with lecithin:cholesterol acyltransferase (LCAT)

8

Apoliproteins: ApoE

Associated lipoprotein?
Function/characteristics?

Chylomicron remnants, VLDL, IDL, HDL

Binds to LDL receptor

9

Lipoprotein lipase (LPL):

What time of enzyme is this?
In what tissues is it concentrated?
What is its function?

Serine esterase

Muscle & adipose tissue

Main enzyme in processing chylomicrons & VLDL (via hydrolysis of FAs from TAGs)

10

Hepatic lipase:

What are its functions?
What does it respond positively to? Negatively to?

Continues lipolysis of VLDL & IDL ➡️ LDL
Hydrolyzes PLs and HDL-TAGs

➕: androgens
➖: ⬆️ estrogen

11

Lecithin:cholesterol acyltransferase (LCAT):

What does it circulate with?
What is its function?

HDL, LDL, ApoD, Cholesteryl ester transfer protein (CETP)

Transfers LCFAs from PLs to cholesterol ➡️ forms cholesterol esters (for storage & transport in lipoprotein core)

12

Acyl-CoA:cholesterol acyltransferase (ACAT):

Location?
What is its function?

Intracellular enzyme

Esterifies free cholesterol via linking to an FA ➡️ for storage in liver parenchymal cells

13

What is the forward cholesterol transport pathway?

Transport cholesterol from liver ➡️ peripheral cells & tissues

(via VLDL ➡️ IDL ➡️ LDL)

14

What is the reverse cholesterol transport pathway?

Transport of cholesterol from extrahepatic tissues ➡️ liver, for excretion in bile

(via HDL)

15

Hyperlipoproteinemia: phenotype I

Lipoprotein in excess?

Chylomicrons

16

Hyperlipoproteinemia: phenotype IIa

Lipoprotein in excess?

LDL

17

Hyperlipoproteinemia: phenotype IIb

Lipoprotein in excess?

LDL
VLDL

18

Hyperlipoproteinemia: phenotype III

Lipoprotein in excess?

Beta-VLDL

19

Hyperlipoproteinemia: phenotype IV

Lipoprotein in excess?

VLDL

20

Hyperlipoproteinemia: phenotype V

Lipoprotein in excess?

Chylomicrons
VLDL

21

Lipid-lowering drugs: Cholestyramine & colestipol

Characteristics/Function?

Non-absorbable resins

Interrupt enterohepatic circulation of bile acids

22

Lipid-lowering drugs: Nicotinic acid

Characteristics/Function?

➖ hepatic secretion of VLDL, suppresses mobilization of FAs ➡️ ⬇️ VLDL & LDL

23

Lipid-lowering drugs: Clofibrate, gemfibrozil

Characteristics/Function?

➕ LPL ➡️ rapid turnover of VLDL

Gemfibrozil: ➖ VLDL secretion

24

Lipid-lowering drugs: Probucol

Characteristics/Function?

Blocks intestinal cholesterol transport ➡️ ⬇️ plasma cholesterol (no effect on TAG)

⬇️ HDL cholesterol levels

25

Lipid-lowering drugs: Statins

Characteristics/Function?

➖ regulatory step of cholesterol biosynthesis

➖ hepatic cholesterol synthesis, upregulates LDL receptor activity ➡️ ⬇️ serum cholesterol & LDL cholesterol