Blood Lipoproteins Lec 2 Flashcards
What are the lipoprotein complexes?
Chylomicrons very low density lipoproteins (VLDL) intermediate density lipoproteins (IDLs) low density lipoproteins (LDLs) hight density lipoproteins (HDLs)
What is the purpose of lipoproteins?
to protect their hydrophobic cargo from aqueous env. while shuttling from tissue to tissue
What is in the core of the lipoprotein (the hydrophobic core)?
Triacylglycerol (TAG)
cholesterol esters
how is the density determined for lipoproteins?
protein to lipid ratio–ex: chylomicrons contain the highest % of lipid (primarily TAG) and the lowest % protein
When performing electrophoresis which lipoprotein particle is going to travel the furthest and which the least?
Furthest—HDL
Least– chylomicron
When performing ultracentrifugation which lipoprotein will sit on top and which will be at bottom?
Top- chylomicrons
bottome- HDL3
What are some of the functions of apoliproteins?
sites for cell surface receptors
enzyme activators involved in lipoprotein metabolism
some–structural components of the lipoprotein
Apo A-I-where is it synthesized and whats its function?
Liver and intestine
Structural protein in HDL
Activates LCAT- Transfers FA from lecithin to cholesterol to generate CE
Involved in RCT–transfer of cell cholesterol by ABCA1 to nascent HDL and delivery to liver
What is LCAT and what activates it?
transfers a FA from lecithin to cholesterol to generate CE–activity involved in maturation of HDL
Apo A-I activates it
Apo A-II where is it synthesized and whats its function?
Liver
Structural protein- HDL
Apo B-100 where is it synthesized and whats its function?
Liver
Structural protein-VLDL/LDL
VLDL assembly
LDLR binding
measurements of api B-100 in plasma reflect particle number and higher levels are associated with CVD
Apo B-48 where is it synthesized and whats its function?
Intestine
Chylomicron formation and secretion
Apo C-I where is it synthesized and whats its function?
Liver
LCAT activator–transfers FA from lecithin to cholesterol to generate CE–maturation of HDL
Apo C-II where is it synthesized and whats its function?
Liver
LPL activator
Apo C-III where is it synthesized and whats its function?
Liver
LPL inhibitor
Apo E (E2, E3, E4) where are they synthesized and whats their function?
Recognition by LDL and CM remnant receptors–mediates the hepatic uptake of CM and VLDL remnants as well as IDL
Responsible for clearance of intestinal derived LPs after a meal and for the clearance of VLDL and IDL before they are covered to LDL
What Apo E is a risk for dysbetalipoproteinemia (type III hyperlipidemia) ? and what is seen in the plasma?
Apo E2–characterized by elevation of CM and VLDL remnants in the plasma
Apo(a) where is it synthesized and whats its function?
Liver
modulates thrombosis/thrombolysis
Where are the enzymes involved in the synthesis of the TAG, cholesterol and phospholipids found for chylomicron metabolism?
Smooth ER–> microsomal triglyceride transfer protein (MTP)–loads Apo B-48 with lipid
What enzyme loads Apo B-48 with lipid?
microsomal triglyceride transfer protein (MTP)
When the nascent chylomicron reaches the blood it receives what?
Apo-E and Apo-C
What does Apo-C II come in contact with in the blood and what does this cause?
LPL–activation
-hydrolyzes TAG–yielding fatty acids/glycerol
What occurs after the FAs are formed and all thats left is a chylomicron remnant?
Remnant taken up by liver by Apo-E binding to specific lipoprotein receptors followed by endocytosis/lysosomal hydrolytic enzymes degrading remnant components to cholesterol/AAs/FAs
Where does Apo C-II bind to the LPL?
The C terminal domain–provides specificity
