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Biochemistry

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Lipid

Question
20 out of 26
 

Which receptor are present in liver for uptake of LDL: (AIIMS May 2009)



A Apo E only

B Apo E & Apo A

C Apo A & Apo B 100

D Apo E & Apo B 100

Ans. D Apo E only Ref Harper 209, 26th Edition

The liver and many extrahepatic tissues express the LDL (B-100, E) receptor. It is so designated because it is specific for apo B-100 but not B-48, which lacks the carboxyl terminal domain of B-100 containing the LDL receptor ligand, and it also takes up lipoproteins rich in apo E. This receptor is defective in familial hypercholesterolemia.

Approximately 30% of LDL is degraded in extrahepatic tissues and 70% in the liver. A positive correlation exists between the incidence of coronary atherosclerosis and the plasma concentration of LDL cholesterol.

The density of lipoprotein decreases as the proportion of lipid to protein increased.

Lipoprotein

Source

Diameter (NM)

Density

Composition

Main lipid composition

Apolipoproteins

Protein(%)

Lipid(%)

Chylomicrons

Intestine

90-1000

<0.95

1-2

98-99

Triacylglycerol

A-I, A-II, A-IV, B-48, C-I, C-II, C-III, E

Chylomicrons remnants

Chylomicrons

45-150

<1.006

6-8

92-94

Triacylglycerol,phospholipids, cholesterol

B-48, E

VLDL

Liver (intestine)

30-90

0.95 – 1.006

7-10

90-93

Triacylglycerol

B-100, C-I, C-II, C-III

IDL

VLDL

25-35

1.006 – 1.019

11

89

Triacylglycerol, cholesterol

B-1000, E

LDL

VLDL

20-25

10.19 – 1.063

21

79

Cholesterol

B-100

HDL

Liver, intestine, VLDL, chylomicrons

Phospholipids, cholesterol

A-I, A-II, A-IV, C-I, C-II, C-III, D2, E

HDL

20-25

1.019 – 1.063

32

69

HDL

10-20

1.063 – 1.125

33

67

HDL

5-10

1.125 – 1.210

57

43

Pre β- HDL

<5

>1.210

A-1

Albumin / free fatty acids

Adipose tissue

>1.281

99

1

Free Fatty acids

Lipid Flashcard List

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