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Flashcards in lipid metab Deck (18):

cholesterol synthesis: LCAT and HMG CoA reductase. What do both do?

rate-limiting step catalyzed by HMG-CoA reductase (induced by insulin). this converts HMG-CoA to mevalonate. most plasma cholesteral is esterified by LCAT. LCAT also plas a crytical role in in converting nascent HDL to mature HDL


Statins: target, mechanism (competitive/non-competitive; reversible, irreversible)

competitively and reversibly inhibit HMG-CoA reductase, the rate-limiting step for cholesterol synthesis


Pancreatic lipase: function, location

responsible for the degradation of dietary triglycerides in the small intestines


lipoprotein lipase: function, location

degrades TGs circulating in chylomichrons (which are absorbed from the intestines) and VLDL (very low density lipoprotein). found on vascular endothelial surface


hepatic TG lipase

degradation of TGs remaining as intermediate density lipoprotein



cholesterol ester trasnfer protien mediates the transfer of cholesterol esters to other lipoprotein particles. Important enzyme that transfers cholesterol esters to VLDL, IDL, and LDL from mature HDL.


exogenous lipid transport

dietary lipids are absorbed in the GI tract, and converted to chylomicrons in intestinal mucosa. chylomicrons then enter the general circulation, where they are processed by lipoprotein lipase. the end result are chylomicron remnants, which are taken up by the liver


endogenous lipid transport

liver synthesizes VLDL (very low density lipids). VLDL carries fat to tissues. VLDL may be converted to LDL, which can be taken up by periphery or again by lipids.



synthesized in blood from various souces. picks up peripheral cholesterol and transports it back to the liver. aka scavenging protein.


Apolipoprotein E function, relevant molecs.

mediates remnant reuptake. seen chylomicrons, chylomicron remnants, VLDL, IDL, and HDL


apolipoprotein A-1 function, relevant molecs.

activates LCAT (which esterifies cholesterol). works on chylomicrons and HDL


apolipoprotein C-II function, relevant molecs.

lipoprotein lipase cofactor (LPL is found on the vascular endothelium and degrades triglycerides and VLDL. also works on HDL


poplipoprotein B-48 function, relevant molecs.

mediates chylomicron secretion. affects chylomicrons and chylomicron remnants


apolipoprotein B-100. function, relevant molecs.

binds LDL receptor. affects VLDL, IDL, and LDL.


LDL: formation/secretion, what they do

synthesized by liver and transports cholesterol from liver to tissues.


VLDL: formation/secretion, what they do

delivers hepatic triglycerides to peripheral tissues


IDL: formation, what they do

formed in the degradation of VLDL (and chylomicrons). delivers TGs and cholesterol to the liver. (IDL that isn't taken up by the liver becomes LDL)


chylomicrons: function, who secretes them

delivers dietary TGs to peripheral tissue. delivers cholesterol to liver in the form of chylomicron remnants. secreted by intestinal epithelial cells.