276
CASE FILES: BIOCHEMISTRY
Table 30-1
MAJOR APOPROTEINS INVOLVED IN LIPID TRANSPORT
BY LIPOPROTEINS
APOPROTEIN
LOCATION
FUNCTION
A
HDL
Activates LCAT (lecithin-cholesterol
acyltransferase)
B-48
Chylomicrons, chylomicron
remnants
Structural, binds to B-48:E receptor
in liver
B-100
VLDL, IDL, LDL
Structural, binds to LDL receptor in
liver and extrahepatic tissues
C-II
Chylomicrons, VLDL,
(IDL), HDL
Binds to and activates lipoprotein
lipase
E
Chylomicrons, chylomicron
remnants, VLDL,
(IDL), HDL
Structural, binds to B-48:E receptor
in liver
The major classes of lipoproteins (Table 30-1) and some of their properties
are
Chylomicrons
• Lowest density
• Transport dietary lipids from the intestine to target tissues
Very-low-density lipoproteins (VLDLs)
• Produced by liver cells to transport endogenously synthesized lipids to
target cells
• Production controlled by lipid availability
• Contain five different apoproteins
Intermediate density lipoproteins (IDLs)
Low-density lipoproteins (LDLs)
• Primarily cholesteryl esters
• Apoprotein B-100
High-density lipoproteins (HDLs)
• Secreted by liver and intestine
• Contains apoprotein A-1
• “Good cholesterol,” high levels associated with low incidence of
atherosclerosis
previous page 290 Case Files   Biochemistry read online next page 292 Case Files   Biochemistry read online Home Toggle text on/off