Lipids and Lipoproteins - Lipoproteins Flashcards
What are lipoproteins?
Vehicles that transport cholesterols, TAGs and fat-soluble vitamins
Vehicles that transport cholesterols, TAGs and fat-soluble vitamins
Lipoproteins
Ligands that bind receptors to internalize lipoproteins
Apolipoproteins
Outer shell of lipoproteins consists of?
Phospholipids
Apolipoproteins
Free cholesterol
Inner core of lipoproteins consists of?
Cholesterol
Cholesterol Esters
TAGs
Fat soluble vitamins
What are the 5 types of Lipoproteins?
- Chylomicrons
- VLDL
- IDL
- LDL
- HDL
What is the largest lipoprotein?
Chylomicron
What is the smallest lipoprotein?
HDL
What is the most dense lipoprotein?
HDL
What is the least dense lipoprotein?
Chylomicron
What lipoprotein contains the most TAGs and least protein?
Chylomicrons
What lipoprotein contains the most proteins and least TAGs?
HDL
Bad cholesterol
LDL
Good cholesterol
HDL
Apo-48
Facilitates transport
ApoC - II
Activates capillary lipoprotein lipase
ApoE
Facilitates uptake into the liver
ApoB - 100
Facilitates uptake into cells
ApoA - 1
Activates enzyme that esterifies cholesterol
What apolipoproteins do chylomicrons have?
Apo-48
ApoC - II
ApeE
What apolipoproteins do VLDL have?
ApoB - 100
ApoC - II
ApoE
What apolipoproteins do IDL have?
ApoB-100
ApoE
What apolipoproteins do LDL have?
ApoB-100
What apolipoproteins do HDL have?
ApoA - 1
ApoC - II
ApoE
Describe chylomicron processing
- Lipoproteins (Apo-48, ApoC - II, ApoE) are added to chylomicron
- ApoC - II activates lipoprotein lipase that hydrolyzes TAGs
- Remnants of chylomicron are endocytosed by the liver with binding of ApoE
When you hydrolyze TAGs, what do you get?
Glycerol and Free Fatty Acids
Describe VLDL, IDL, LDL processing
- VLDL (ApoB-100, ApoC-II, ApoE) assembled in liver and sent to blood stream
- Lipoprotein lipase hydrolyzes TAGs and ApoC-II is released == forms IDL (ApoB-100, ApoE)
- IDL delivers cholesterol to the liver and loses more TAGs and ApoE == becomes LDL (ApoB-100)
- LDL delivers cholesterol to liver and peripheral tissues via binding of ApoB-100
Major carrier of cholesterol in the blood and takes it to peripheral tissues?
LDL (bad cholesterol)
When LDL’s ApoB-100 binds receptor on target tissue, what happens next?
Receptor mediated endocytosis:
- Receptor and LDL brought into cell in endosome
- LDL dissociates from receptor
- LDL releases cholesterol contents
- Receptor returned to cell surface
Describe HDL processing
- HDL picks up cholesterol from tissues due to ApoA - 1
- LCAT esterifies cholesterols
- HDL delivers cholesterols to liver for excretion
What does HDL donate and receive from chylomicrons?
ApoC - II
ApoE
What does HDL transfer to VLDL, IDL and LDL in exchange for TAGs and phospholipids?
Cholesterol esters
What facilitates HDL exchanges with VLDL, IDL and LDL?
CETP
What does HDL remove from peripheral tissues?
LDL!!!
Increased HDL ____ risk for coronary artery disease
DECREASES
HDL is needed for maturation of?
Chylomicrons
Tangier Disease
HDL deficiency, accumulation of cholesterol
– can cause atherosclerosis
Type 1 Hyperlipoproteinemia
Inability to hydrolyze TAGs in chylomicrons and VLDL
= HIGH TAGs
What are possible deficient with Type 1 Hyperlipoproteinemia?
ApoC - II
Lipoprotein lipase
If lipoprotein lipase is deficient, when will it be noticed?
Infancy
If ApoC - II is deficient, when will it be noticed?
Post - adolescence
Physical symptoms of Type 1 Hyperlipoproteinemia?
Xanthomas
Creamy blood
Type 2 Hyperlipoproteinemia
Deficient LDL receptors = defect in LDL uptake
== HIGH CHOLESTEROL IN BLOOD
How is Type 2 Hyperlipoproteinemia inherited?
Autosomal dominant
What does Type 2 Hyperlipoproteinemia result in?
Increased LDL in blood vessels (goes into intima)
– Stimulates ATHEROSCLEROSIS
Symptoms of Type 2 Hyperlipoproteinemia?
Xanthomas
Angina pectoris
What enzyme esterifies cholesterols and puts them in HDL core?
LCAT