Pallas- Lipoprotein Metabolism Flashcards
(32 cards)
What is found at shell of lipoproteins?
- amphipathic apolipoproteins/lipids (non-esterified cholesterol and phospholipids)
What is found at neutral lipid core of Lipoproteins?
- hydrophobic lipids, triglycerides, and cholesterol esters
How can you obtain TG and cholesterol?
- exogenous (diet)
2. endogenous (de novo synthesis)
density is _____ related to lipid content and ______ to particle size
- directly; inversely
which lipoprotein classes are the primary carriers of cholesterol?
- LDL’s and HDL’s
lower density lipoproteins have _____ total protein percentage
- decreased total protein percentage (protein is more dense than lipid, so if you’re less dense, you’re more lipid and less protein)
What is IDL
- Intermediate density
- aka vldl remnant
why is HDL good
- does reverse cholesterol transport to move LDL’s back to liver
what are the five classes of apolipoproteins
apoA through apoE
Name some funcitons of apolipoproteins
- some bind to cell surface receptors on specific cell types to target the lipoproteins to be endocytosed by the cell
EX: ApoB-100 and ApoE
- activators of enzymes involved in lipoprotein metabolism
- ex: apoC-II –> activates lipoprotein lipase (LPL)
Define the three lipoprotein metabolism pathways
- Exogenous pathway – transport of lipids from dietary fat via chylomicrons primarily to peripheral tissues
- endogenous pathway: transport of lipids synthesized primarily by the liver to peripheral tissues via VLDL’s
- Reverse cholesterol transport – transport of cholesterol from the peripheral tissues to the liver of via HDL’s
Why is reverse cholesterol transport to liver important
- Liver is the only organ that can get rid of cholesterol via turning into bile acids or excreting it along with bile… without this function, we just have cholesterol everywhere peripherally
where do pathway 1 and 2 converge
- lipoprotein lipase stimulated by Apo C-II to:
- release TAG to cells
- createIDL and chylomicron remnants
what is fate of chylomicron remnants
- go to liver
what is fate of IDL remnants
- goes to liver like chylomicron remnants
- converted by hepatic lipase to lDL, where it can go to the liver OR go back to peripheral cells via receptor-mediated endocytosis
HDL’s tend to uptake cholesterol from which cells?
- macrophages that have taken up cholesterol
what important apolipoproteins are on chylomicrons?
- apoB-48 – tethers remnants to heaptocytes
2. apoE – responsible for binding for uptake via endocytosis
how are VLDL’s made? what apolipoprotein is htere?
- Liver… contains apoB 100
what other apolipoproteins are a part of VLDL and how do they get there?
- ApoCs and apoE, along with cholesterol esters… acquired from HDL in ciruculation
How is IDL taken up into liver?
- via apoE/remnant receptor
what is the other fate of IDL? what apolipoprotein sits on it?
- hepatic lipase on IDL makes it lose apoE and cleave cholesterol esters to give you a lower density LDL… only has apoB-100 on it
Name fates of low density lipoproteins
- MOST is uptake by liver
- rest is uptake/delivery to extrahepatic tissues
Of the LDL’s taken up by liver, what is their fates?
- 3/4 receptor mediated tkaen up
1/4 non-rceptor mediated
Of the LDL’s taken up by other tissues, what are fates
2/3 R mediated
1/3 non-R mediated
