What is the main purpose of lipoproteins?
to transport lipids and fat-soluble vitamins in the blood
What is the structural protein for chylomicrons and chylomicron remnants?
Apo B-48, made in the intestine
What is the activator of lipoprotein lipase?
Apo C-II ("borrowed from HDL)
What are the two functions of Apo B-100?
Structural component of VLDL, IDL, and LDL
Ligand for LDL receptor
What are the two functions of Apo A-I?
Structural component of HDL
Activator of PCAT enzyme
What is the function of Apo E?
Ligand for hepatic Apo E receptor for CM remnants clearing
Ligand for Apo E receptor for IDL clearing
What receptor in the liver binds to the chylomicron remnant?
Apo E receptor
What receptor in extrahepatic tissue and the liver binds to LDL?
Apo B-100 receptor
What do bile acid resins (like cholestyramin) do to the absorption of bile salts?
Prevents the re-absorption of bile salts and forces the liver to use more cholesterol for bile salt synthesis.
What two effects will the decrease in cytosolic cholesterol result in?
Increase in LDL receptor expression (decrease in serum cholesterol)
Increase in HMG-CoA reductase expression (increase in de novo synthesis of cholesterol)
What are the three main functions of HDL?
Resevoir for apolipoproteins (Apo C-II and Apo E)
HDL uptake of unesterified cholesterol
Esterification of cholesterol (by PCAT)
What is the function of CETP?
moves CEs from HDL to VLDL in exchange for TG
Where does HDL get its cholesterol?
Macrophages (foam cells) --> antiatherogenic
Important stuff from lecture 39: Lipoprotein metabolism