Review 7: Lipoproteins Flashcards
(20 cards)
Where are chylomicrons formed?
small intestine
Where are VLDL and HDLs?
in the liver
what does Apo-CII do?
activates lipoprotein lipase (LPL) so tags and such can be broken down
What does Apo E do?
it is a remnant receptor
Chylomicrons are formed in the intestines along with Apo __ and Apo __
A-1 and B-48
Chylomicrons gain Apo __ and Apo ____ from HDL in the plasma
E and C-II
What is the function of LPL (lipoprotein lipase)?
converts TAGs to FFAs and glycerol
How are chylomicron remnants removed once their contents have been broken down?
receptor-mediated endocytosis
Apo E binds to LDL receptor
What is the source of Apo CII, Ai , and E?
HDL
Chylomicrons transport __________ TAGs and cholesterol, VLDLs transport ___________ TAGs and cholesterol
exogenous (dietary); endogenous
When do VLDLs turn into IDLs?
when they lose their TAG and shrink
When do IDLs become LDLs?
when Apo C0II and Apo E are transferred to HDL
How is LDL removed from circulation?
binding of Apo B-100 to the LDL receptor (found on hepatic and non hepatic tissue)
What is the marker on LDL that is recognized by the LDL receptor?
Apo B-100
What are the two ways LDL can be taken up by the cell?
1) receptor mediated (Apo B-100 binds to LDL receptor)
2) receptor independent (pinocytosed)
When is receptor independent LDL uptake most important?
under conditions of high cholesterol (receptors are downregulated so this receptor independent pathway steps up to the plate)
How is oxidation of LDL dangerous?
macrophages take up oxidized LDL and become foam cells which then accumulate, release cytokines that promote proliferation of smooth muscle cells and calcification of plaque
Where are nascent HDLs synthesized?
liver and small intestine
What is the marker on HDL that is recognized by the receptor?
Apo A-1
What is the function of statins?
down regulate activity of HMG CoA-reductase so less cholesterol is produced – this upregulates LDL receptors which promotes removal of circulating cholesterol
