• 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
Anatomy of a Lipoprotein
Fig. 25-1
CHYLOMICRON
De
nsity
(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
CHYLOMICRON
REMNANTS
LDL
HDL
2
HDL
3
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
TRIGLYCERIDE-RICH LIPOPROTEINS
CHYLOMICRON
VLDL
TRIGLYCERIDE
CHOLESTEROL
ESTERS
PHOSPHOLIPIDS
FREE
CHOLESTEROL
PROTEINS
30-80 NM
80-1000 NM
90-95%
2-4%
2-6%
~1%
1-2%
50-65%
8-14%
12-16%
4-7%
5-10%
CHOLESTEROL-RICH LIPOPROTEINS
LDL
HDL
TRIGLYCERIDE
CHOLESTEROL
ESTERS (CE)
PHOSPHOLIPIDS
FREE
CHOLESTEROL
PROTEINS
5-6%
~7%
10-20%
35-45%
25%
22-26%
6-15%
~5%
22-26%
~45%
20-25 nm
8-13 nm
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
Tg
CE
Tg
CE
Tg
B
CE
Tg
CE
Tg
CE
Tg
B
B
Tg Tg Tg
Tg Tg Tg
Tg
Tg
Tg
Tg
CE CE
CE CE
CE
B
Tg Tg Tg
Tg Tg Tg
Tg
Tg
Tg
Tg
CE CE
CE CE
CE
B
Tg Tg Tg
Tg Tg Tg
Tg
Tg
Tg
Tg
CE CE
CE CE
CE
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
CE
CE
CE
B
Tg
VLDL
IDL
LDL
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
Dietary Lipoproteins
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.