Flashcards in Lipoprotein Lecture (Lecture 2) Deck (24):
Two ways lipids are suspended in blood
(1) transport of fatty acids in association with albumin
(2) components of lipoproteins
Features of lipoproteins
(1) surface composed of a monolayer of amphipathic lipids (phospholipids and unesterified cholesterol) and proteins
(2) anhydrous cose, composed of triacylglycerols and cholesterol esters (anhydrous core - containing no water)
What are apolipoproteins?
proteins that bind lipids to form lipoproteins; lipid-binding proteins in the blood responsible for the tranport of triacylglycerides, plasma lipids, cholesterol, estified cholesterol
What does "Apo" designate?
"Apo" designates the protein in its lipid-free form
Purpose of apolipoprotein
(1) act as recognition sites or ligands for receptors
(2) act as structural components
(3) act as activators or coenzymes for enzymes involved in lipid metabollism
How do we make distinctions between each lipoprotein?
tissue of origin and average composition
Size and density of lipoprotein particles
(1) chylomicrons - lipoprotein particles lowest in density and largest in size, contain the highest percentage of lipid and the lowest percent of protein
(2) VLDLs and LDLs are successively denser, having higher ratios of protein to lipid
(3) HDLs are the densest
How are plasma lipoproteis separated
separated on the basis of their electrophoretic mobility or on the basis of their densities by an ultracentrifugation
How are apolipoproteins divided
by structure and function into five ajor classes, A through E, with most classes having subclasses
What are the 2 basic phases to lipoprotein metabolism?
Processing of lipoprotein
undergo changes in composition of both surface and core components, during transit in the circulation, converting to the remnant form
Clearance of lipoprotein
from the blood, via a receptor-mediated endocytotic process
Source and function of chylomicrons?
Intestine. Transport of TAG
Major apolipoproteins of chylomicrons?
B48, CII, CIII, E
Source and function of VLDL?
Liver. Transport of endogenously synthesized TAG
Major apolipoproteins of VLDL?
B100, CII, CIII, E
Source and function of LDL?
Formed in circulation by partial breakdown of IDL. Delivers cholesterol to peripheral tissues
Major apolipoproteins of LDL?
Source and function of HDL?
Liver. Removes "used" cholesterol from tissues and takes it to liver
Major apolipoproteins of HDL?
AI and AII, CII, CIII, E
Pathways for lipoprotein metabolism?
(1) exogenous pathway
(2) endogenous pathway
(3) reverse cholesterol transport pathway
chylomicrons, dealing with dietary lipids
VLDL, IDL, LDL, dealing largely with de novo synthesized lipids