1. Plasma LIPOPROTEINS METABOLISM & DISORDERS Basil OM Saleh

2. Lipoproteins LPs are spherical structures composed from lipids and proteins and function in supporting the transport of lipids in circulation. In these structures the water insoluble lipids (TG and esterified cholesterol) are oriented to the core of the spherical LP, while the water soluble lipids(PL, Free chol. ) are directed to the surface of LP.

3. However, these structures in their later form still relatively insoluble in systemic circulation and need for addition of specific proteins, called apolipoproteins(apoLPs) to confer them sufficient water solubilitiy and so transporting in blood.

4. Apolipoproteins Structural determinants of lipoproteins
Enzyme cofactors
Ligands for binding to lipoprotein receptors
The apoLPs; apo AI,AII, Apo B48, apo B100, apo CI, apo CII, apo CIII, apo E 2, apo E3, apo E4

6. Anatomy of a Lipoprotein
Fig. 25-1

7. There are five major LPs in blood of human body,along with additional sixth one LP(a) that is related to LPs structurally but not functionally

8. 1. Chylomicron 2. Very Low Density Lipoprotein (VLDL) 3
1.Chylomicron 2.Very Low Density Lipoprotein (VLDL) 3.Intermediate Density Lipoprotein(IDL) 4.Low Density Lipoprotein(LDL) 5.High Density Lipoprotein(HDL)  

9. VLDL IDL REMNANTS LDL HDL2 HDL3 CHYLOMICRON Density (g/ml)
Diameter (nm)
1000 80 60 40 20 10 5
1.20
1.10
1.06
1.02
1.006
0.95
VLDL
IDL
REMNANTS
LDL
HDL2
HDL3

11. Plasma Lipoproteins Classes & Functions
Chylomicrons
Synthesized in small intestine
Transport dietary lipids
98% lipid, large sized, lowest density
Apo B-48
Receptor binding
Apo C-II
Lipoprotein lipase activator
Apo E
Remnant receptor binding

12. TRIGLYCERIDE-RICH LIPOPROTEINS
CHYLOMICRON
VLDL
TRIGLYCERIDE
CHOLESTEROL
ESTERS
PHOSPHOLIPIDS
FREE
PROTEINS
30-80 NM NM
90-95%
2-4%
2-6%
~1%
1-2%
50-65%
8-14%
12-16%
4-7%
5-10%

13. CHOLESTEROL-RICH LIPOPROTEINS
LDL
HDL
TRIGLYCERIDE
CHOLESTEROL
ESTERS (CE)
PHOSPHOLIPIDS
FREE
PROTEINS
5-6%
~7%
10-20%
35-45%
25%
22-26%
6-15%
~5%
~45%
20-25 nm
8-13 nm

14. CE B Tg
CE Tg
Tg Tg Tg
CE CE
VLDL IDL LDL

15. Plasma Lipoproteins Classes & Functions
Very Low Density Lipoprotein (VLDL)
Synthesized in liver
Transport endogenous triglycerides
90% lipid, 10% protein
Apo B-100
Receptor binding
Apo C-II
LPL activator
Apo E
Remnant receptor binding

16. Dietary Lipoproteins

17. The formation and secretion of (A) chylomicrons by an intestinal cell and (B) very low density lipoproteins by a hepatic cell. (RER, rough endoplasmic reticulum; SER, smooth endoplasmic reticulum; G, Golgi apparatus; N, nucleus; C, chylomicrons; VLDL, very low density lipoproteins; E, endothelium; SD, space of Disse, containing blood plasma.) Apolipoprotein B, synthesized in the RER, is incorporated into lipoproteins in the SER, the main site of synthesis of triacylglycerol. After addition of carbohydrate residues in G, they are released from the cell by reverse pinocytosis. Chylomicrons pass into the lymphatic system. VLDL are secreted into the space of Disse and then into the hepatic sinusoids through fenestrae in the endothelial lining.