Lipids and Lipoprotein Flashcards
Protein molecules in lipoprotein metabolism, structural proteins, and ligands for cell receptors.
Apolipoproteins
Amphipathic lipids
Phospholipids and non-esterified cholesterol.
Core components of lipoproteins
Neutral lipids: Triglycerides (TAG), cholesterol esters, free fatty acids (NEFA).
HDL surrogate markers
Apolipoproteins A-I
Apolipoprotein A-I function
HDL structural protein, LCAT activator.
Plasma concentration of A-I
100-200 mg/dL.
Apolipoprotein A-II function
HDL structural protein.
Plasma concentration of A-II
20-50 mg/dL.
Apolipoprotein A-IV function structural protein for
CM, VLDL, HDL.
Plasma concentration of A-IV
10-20 mg/dL.
Apolipoprotein B-100 function
Structural protein for VLDL, IDL, LDL; LDL receptor ligand.
Plasma concentration of B-100
70-125 mg/dL.
Apolipoprotein B-48 function
Structural protein for CM; remnant receptor ligand.
Plasma concentration of B-48
<5 mg/dL.
Apolipoprotein C-I function
Structural protein for CM, VLDL, HDL.
Plasma concentration of C-I
5-8 mg/dL.
Apolipoprotein C-II function
Structural protein; LPL cofactor.
Plasma concentration of C-II
3-7 mg/dL.
Apolipoprotein C-III function
Structural protein; LPL inhibitor.
Plasma concentration of C-III
10-12 mg/dL.
Apolipoprotein E function
Recognition factor for targeting CM and VLDL remnants to hepatic receptor.
Plasma concentration of E
3-15 mg/dL.
Catalyzes the esterification of cholesterol
Lecithin cholesterol acyltransferase (LCAT)
Mediates endocytosis of lipoproteins, especially LDL
LDL Receptor (LDL-R)
Catalyzes hydrolysis of TG in lipoproteins, releasing free fatty acids and glycerol
Lipoprotein lipase (LPL)
Chylomicron Density
<0.93
VLDL Density
0.93 - 1.006
LDL Density
1.019 - 1.063
HDL Density
1.063 - 1.21
Electrophoretic Mobility of apolipoproteins from origin to anode
Chylomicron, B-LDL, IDL, Pre-B (VLDL), A (HDL)
Ultracentrifuge Density (Top to Bottom)
Chylomicron, VLDL, IDL, LDL, HDL
Chylomicron Major Component
Triglyceride (Exogenous), Apolipoproteins B48, C, E
VLDL Major Component
Triglyceride (Endogenous), Apolipoproteins B100, C, E
LDL Major Component
Cholesterol (>50%), Apolipoprotein B100
HDL Major Component
Protein 50% and Phospholipids, Apolipoproteins A-I, A-II, C, E
Chylomicron transportation
Transports Exogenous Lipids
VLDL transportation
Transports Endogenous Lipids
LDL transportation
Transports Cholesterol to Peripheral Tissues (Atherogenic)
HDL
Reverse Cholesterol Transport (Tissues to Liver)
Involves lipid absorption, exogenous, endogenous, and reverse cholesterol transport pathways
Lipoprotein Metabolism
Lipid Absorption
Conversion of dietary lipids into more polar compounds by Pancreatic Lipase facilitated by bile
Steatorrhea
Excess fat in feces, may indicate infection or lipid absorption issue
Triglyceride Conversion (Lipid Absorption)
Triglyceride → Monoglycerides for better absorption
Cholesterol Ester Conversion
Cholesterol esters → Free cholesterol for absorption
Phospholipid Conversion for absorption
Phospholipids → Lysophospholipids
Exogenous Pathway
Chylomicrons carry dietary lipids from the intestine to circulation
Lipoprotein Lipase (LPL) Action
Hydrolyzes triglycerides in chylomicrons into fatty acids and glycerol
Lipolytic product of VLDL catabolism, intermediate between VLDL and LDL in density, protein, and lipid content
IDL (Minor Lipoprotein)
Floating B-lipoprotein with high cholesterol content, seen in type 3 hyperlipoproteinemia or dysbetalipoproteinemia
B-VLDL
Prothrombotic lipoprotein with Apo(a) homologous to plasminogen, associated with stroke, MI, and CHD
Lp(a)
Abnormal lipoprotein associated with obstructive biliary disease and LCAT deficiency, composed of phospholipids and non-esterified cholesterol
LpX
Minor lipoprotein found with Albumin, involved in lipid transport
Apo C w/ Albumin
LDL Density & Mobility
LDL density and mobility are similar to VLDL, with a role in cholesterol transport to peripheral tissues