Lipoproteins Flashcards
(35 cards)
Name the lipoproteins in order of increasing density
Chylomicrons, VLDL, IDL, LDL, HDL
What determines lipoprotein density?
Lipid content
eg Chylomicrons are the least dense because they have the highest lipid content
Where is VLDL created?
liver
Where are chylomicrons synthesized?
intestinal epithelium after a meal, they disappear a few hours later
What is the first step in digestion of dietary lipids?
Emulsification by bile salts. This increases the surface area of the lipid so that it can contact the digestive enzymes.
What are the intestinal enzymes thats breakdown dietary triglycerides, cholesterol esters, and phospholipids?
pancreatic lipase: cleaves triglyceride ester bonds
colipase: helps attach pancreatic lipase to micelles
cholesterol esterase: hydrolyzes cholesterol esters
phospholipases: break down phospholipids (e.g. A2)
Which Apoprotein is responsible for the formation of chylomicrons?
B-48
How are fatty acids and cholesterol transferred across intestinal mucosa?
monoglycerides are absorbed passively
microsomal triglyceride transferase: brings in triglycerides, attach to ApoB-48
Once chylomicrons are formed in intestinal epithelium where do they go?
lymphatic circulation
Where do chylomicrons enter the blood stream?
They are transferred from lymphatics to the bloodstream at the left SC vein/thoracic duct
What is lipoprotein lipase and where is it located?
It is embedded in capillary walls. It delipidates chylomicrons, freeing fatty acids so that they can enter cells.
Which Apoprotein activates lipoprotein lipase?
C-II
Where are chylomicron remnants degraded?
THE LIVER!!!!
Largest lipoprotein
Chylomicron
Which apoproteins do chylomicrons contain and what do they do?
B-48: form chylomicrons
A-I: activates LCAT(esterifies cholesterol) and binds HDL receptor
C-II: activates lipoprotein lipase
E: recognizes LDL receptor
Where is LDL receptor?
on target tissues
What is the main carrier of endogenously synthesized triglycerides?
VLDL
Which apoproteins does VLDL contain and what do they do?
B-100: binds LDL receptor (docking)
C-II: activates lipoprotein lipase
E: recognizes LDL receptor
Where is LDL formed?
circulation
What does LDL do?
transport cholesterol to tissues
What apoprotein does LDL contain?
B-100:binds LDL receptor
What is the smallest lipoprotein?
HDL
What is the most abundant lipoprotein?
HDL
Which lipoprotein distributes cholesterol to other lipoproteins?
HDL
