Lipid Transport Flashcards
How are lipids transported in plasma?
As lipoproteins
What does a lipoprotein consist of?
Lipid core + single surface layer of: amphipathic phospholipid, cholesterol, and apoprotein (protein moiety)
How are lipoproteins separated into chemical classes? What are the 5 apoprotein names?
Ultracentrifugation; A, B48, B100, C, E
What is the location + function of apoprotein A?
HDL; activator for enzyme LCAT (lecithin cholesterol acyl transferase)
What is the location + function of apoprotein B48?
Chylomicron; ligand
What is the location + function of apoprotein B100?
VLDL/LDL; ligand
What is the location + function of apoprotein C?
HDL; structural
What is the location + function of apoprotein E?
HDL, ligand
What is the largest lipoprotein? What is it’s density? How is it transported?
Chylomicron, least dense, Dietary fats aka EXOGENOUS lipids
Explain the clearance and reuptake of Chylomicrons
Clearance from blood is rapid
Liver reuptakes via receptor mediated endocytosis
What is the 2nd largest lipoprotein? What is it’s density? How is it transported?
VLDL, ENDOGENOUS lipids made in liver - mainly TAG and some CEs (cholesterol esters)
How do VLDL FAs enter tissue (especially adipose)?
Lipoprotein lipase in cell walls of capillaries allow FAs to enter tissues
What is the 3rd largest lipoprotein? What is it’s density? How is it formed?
LDL, after the action of lipoprotein lipase on VLDL, LDL is formed - mainly CEs
What moves into tissue when LDL binds to B100 receptors in what location?
CE, B100 receptors in arterial SmM cells, fibroblasts, and macrophages
What is the smallest lipoprotein? What is it’s density? How is it transported? What is this transport called?
HDL; mainly protein carries cholesterol BACK to liver: Reverse Cholesterol transport
In reverse cholesterol transport, where is nascent HDL (discoidal) synthesized?
Liver
What is the 2nd step of reverse cholesterol transport? What enzyme is involved and what is the action of this enzyme? What happens to the products of this enzyme’s action?
DIscoidal HDL (hockey puck) uptakes + esterfies cholesterol from tissue, becoming HDL3 (baseball); LCAT converts free cholesterol into esters + lysolecithin: CEs move into HDL core + Lysolecithin is transferred to albumin
In the 3rd step of Reverse cholesterol transport, what happens to HDL3?
Becomes bigger + less dense = HDL2 (basketball)
In the 4th step of Reverse cholesterol transport, what happens to HDL2? What enzyme?
Hepatic lipase allows cholesterol + CEs to unload in liver, forming HDL3
In the 5th step of Reverse cholesterol transport, what happens to HDL3?
HDL3 reenters circulation
What is the impact of sex hormones on Hepatic Lipase?
Increased by androgens (testosterones) = lower HDL in men
Decreased by estrogens = ^HDL in menstruating women
What does ^levels HDL do?
Reduce risk of atherosclerosis
What factors ^HDL?
Reduced refine carb diets, ^action of lipoprotein lipase (exercise), estrogen (pre-menopausal women)
