Lipoproteins Clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood
Dec 25, 2015
Lipoproteins Clusters of lipids
associated with proteins that serve as transport vehicles for lipids in the lymph and blood
Lipoproteins Distinguished by size
and density Each contains
different kinds and amounts of lipids and proteins The more lipid, the
lower the density The more protein, the
higher the density
Lipoproteins Chylomicrons VLDL – Very low density lipoprotein IDL – Intermediate density
lipoprotein LDL – Low density lipoprotein HDL – High density lipoprotein
Distinguished by size and density
Each contains different kinds and amounts of lipids and proteins The more lipid, the
lower the density The more protein, the
higher the density
Lipoproteins
The Origins & Major Functions of Lipoproteins
Functions of Chylomicrons Made by intestinal cells Most of lipid is triglyceride Little protein
ApoA-I, ApoA-II, ApoB-48, ApoC Deliver fatty acids via lipoprotein
lipase
Chylomicron remnants Lipoprotein particle that remains
after a chylomicron has lost most of its fatty acids Taken up by liver Contents reused or recycled
Further Delivery of Lipids in Body
Liver Synthesizes & metabolizes lipids “Central command center” for
relation of lipid metabolism Makes additional lipoproteins
Very-Low-Density Lipoproteins (VLDL)
Made by liver Contains large amounts of
triglyceride Delivers fatty acids to cells More dense than chylomicrons A bit more protein (8%)
ApoB-100, ApoC, ApoE
Intermediate-Density Lipoproteins (IDL) Lipoprotein that results from loss of fatty
acids from VLDL Major lipid is cholesterol esters Proteins similar to VLDL but greater
percentage (15%) ApoB-100, ApoC, ApoE
Taken up by liver or remain in circulation Converted to low-density lipoproteins (LDL)
Low-Density Lipoproteins (LDL) “Bad” cholesterol; major lipid in LDL Delivers cholesterol from liver to cells
Cell membranes Hormone production
Protein (21%) ApoB-100 Binds to specific LDL receptor
LDL receptors Membrane-bound proteins that bind LDL,
causing them to be taken up & dismantled
Effect of Diet on LDL Concentrations Increase LDL
SFAs Trans fatty acids High cholesterol
intake Lifestyle factors Genetics
Decrease LDL High PUFA diet Ω-3 fatty acids Dietary fiber Lifestyle factors Genetics
High-Density Lipoproteins (HDL) “Good” cholesterol; major lipid is phospholipid Lipoprotein made by liver that circulates in the
blood to collect excess cholesterol from cells Lowest lipid-to-protein ratio
Protein (50%) ApoA, ApoC, ApoE
Reverse cholesterol transport Salvage excess cholesterol from cells Transported back to liver
Effects of Diet on HDL Concentration
What raises HDL? Uncertain if low carbohydrate diets
offer protection High MUFA intake Moderate alcohol consumption Lifestyle factors
Genetic factors influence HDL
Tangier Disease Genetic disorder resulting in
production of faulty HDL particles that cannot take up cholesterol from cells
High risk for developing cardiovascular disease
Properties of Plasma Lipoproteins
Property
Chylomicron
VLDL IDL LDL HDL
Density (g/mL)
<1.006 <1.006
1.006-
1.019
1.019-
1.063
1.063-
1.21
Lipids (%)
98 92 85 79 50
Protein (%)
2 8 15 21 50
Lipids (%) in Plasma Lipoproteins
Lipid Chylomicron
VLDL IDL LDL HDL
Cholesterol 9 22 35 47 19
Triglyceride 82 52 20 9 3
Phospholipid
7 18 20 23 28
Cardiovascular disease (CVD) General term for all diseases of the
heart and blood vessels Atherosclerosis is the main cause of CVD
Atherosclerosis leads to blockage of blood supply to the heart, damage occurs (coronary heart disease, CHD) Cardio = heart Vascular = blood vessels
Lipoproteins and cardiovascular disease (CVD) risk
LDL is positively associated with CVD
HDL is negatively associated with CVD
LDL and atherosclerosis
Recommended blood lipids Total cholesterol: <200 mg/dL LDL cholesterol: <130 mg/dL HDL cholesterol: >35 mg/dL Triglycerides: <200 mg/dL