Lipoprotein and cholesterol

LIPOPROTEIN AND CHOLESTEROL

Angel Das 1 year MBBS Student

LIPOPROTEIN

Lipid

Protein

Lipoprotein

CORE

CHOLESTEROLESTERS

TRIGLYCERIDES

MONOLAYER OF PHOSPHOLIPID

AND CHOLESTERLOL

INTEGRAL APOPROTEINS

PERIPHERAL APOPROTEINS

Structure of lipoprotein

APOPROTEINS

Protein component of lipoproteinPromote transport and uptake of lipids

Act as ligandActivation of enzymes

APOPROTEINS

A B C E• A-l• A-ll

• B-48• B-100

• C-l• C-ll• C-lll

• A-I Liver& intestine

• A-II Liver

• B-48 Intestine• B-100 Liver

• All Liver • Liver

LIPOPROTEINS Lipoprotein Apoproteins

Chylomicron A,B,C,E

VLDL B,C,E

LDL B

HDL A,C,D, E

CLASSIFICATION

Based on density by ultracentrifugationi. Chylomicronsii. Very Low Density Lipoproteiniii.Intermediate Density Lipoproteiniv.Low Density Lipoproteinv. High Density Lipoprotein

COMPOSITION AND SIZE OF LIPOPROTEIN

FUNCTIONS OF LIPOPROTEINS

CHYLOMICRONS transport Triglycerides from intestine to adipose tissues for storage.VLDL carries triglycerols from liver to peripheral tissues.

LDL transports cholesterol from liver to peripheral tissues.HDL transports cholesterol from peripheral tissues to liver“Reverse Cholesterol Transport”

CLINICAL SIGNIFICANCE

HYPERLIPIDEMIAS elevated lipid fraction cholesterol/TAG Frederickson’s Classification

Type l Type ll A Type ll B Type lll Type lV Type V

Type Lipoprotein fraction elevated

Metabolic Defect

Type ll A (Primary Familial Hypercholesterolemia)

LDL LDL receptor defect

Type ll B Hyperlipoproteinemia

LDL & VLDL Apo B

Type lV Familial endogenous Type

VLDL Overproduction of VLDL

HYPOLIPOPROTEINEMIAS

i. Abetalipoproteinemia microsomal triglyceride transfer protein is defective LDL & VLDL decreasesii. Hypo alpha lipoproteinemia HDL level decreasesiii. Tangier Disease absence of ATP binding Cassette Transporter 1, involved in transport of cellular cholesterol to HDL

ATHEROSCLEROSIS

•Deposition of LDL cholesterol in arterial wall, occurs due to damage of endothelium

Physical Properties white crystalline solid substance soluble in ether,chloroform etc. amphipathic in nature abundantly present in nervous tissue

•Have Cyclopentanoperhydrophenanthrene ring system.

CHOLESTEROL

STRUCTURE OF CHOLESTEROL

1. Major structural constituent of the cell membranes and lipoproteins

2. Precursor for Steroid hormones

a. Progesterons

b. Glucocorticoids

c. Mineralocorticoids

d. Androgens & Estrogens

3. Formation of Bile acids and bile salts.

4. Synthesis of Vitamin D

FUNCTIONS OF CHOLESTEROL