1. Lipoprotein Structure and Function
Lipid Transport
Lipoprotein Structure and Function

2. Plasma Lipoproteins Structure figure 19-1
LP core
Triglycerides
Cholesterol esters
LP surface
Phospholipids
Proteins
cholesterol

3. Plasma Lipoproteins Classes & Functions
Chylomicrons
Synthesized in small intestine
Transport dietary lipids
98% lipid, large sized, lowest density

4. Plasma Lipoproteins Classes & Functions
Very Low Density Lipoprotein (VLDL)
Synthesized in liver
Transport endogenous triglycerides
90% lipid, 10% protein

5. Plasma Lipoproteins Classes & Functions
Intermediate Density Lipoprotein (IDL)
Synthesized from VLDL during VLDL degradation
Triglyceride transport and precurser to LDL

6. Plasma Lipoproteins Classes & Functions
Low Density Lipoprotein (LDL)
Synthesized from IDL
Cholesterol transport
78% lipid, 58% cholesterol & CE

7. Plasma Lipoproteins Classes & Functions
High Density Lipoprotein (HDL)
Synthesized in liver and intestine
Reservoir of apoproteins
Reverse cholesterol transport
52% protein, 48% lipid, 35% C & CE

8. Heterogeneity of LDL-particles
Not all LDL-particles the same
Small dense LDL (diameter <256A)
Large buoyant LDL (diameter >256 A)
Lamarche B, St-Pierre AC, Ruel IL, et al. A prospective, population-based study of low density lipoprotein particle size as a risk factor for  Can J Cardiol 2001;17:
2057 men with hi LDL, 5 year follow-up
Those with elevated small dense LDL had RR of 2.2 for IHD compared to men with elevated large buoyant LDL
Detection expensive
Treatment for lowering small dense LDL similar to lowering all LDL (diet, exercise, drugs)
Some drugs (niacin, fibrates) may be more effective at lowering small dense LDL.

9. HDL : Functions Apoprotein exchange Reverse cholesterol transport
provides apo C and apo E to/from VLDL and chylomicrons
Reverse cholesterol transport

10. Reverse cholesterol transport figure 19-6
Uptake of cholesterol from peripheral tissues (binding by apo-A-I)
Esterification of HDL-C by LCAT
LCAT activated by apoA1
Transfer of CE to lipoprotein remnants (IDL and CR) by CETP
removal of CE-rich remnants by liver, converted to bile acids and excreted