Triglycerides are rich in (AIIMS May 2007)
a. The least dense lipoprotein is chylomicron
b. Lipoprotein with max lipid content is chylomicron
c. Lipoprotein with max cholesterol content is LDL
d. Lipoprotein with max phospholipid content is HDL
e. The predominant lipid present in chylomicron is Endogenous TAG
f. The predominant lipid present in VLDL is Endogenous TAG
g. The apoprotein present in nascent chylomicron is apo B 48
h. Apoprotein which activates lipoprotein lipase is apo C II
i. The apoprotein present in LDL is apo B100
Metabolism of lipoproteins
a. What is a lipoprotein?
b. Lipoprotein is required for the transport of nonpolar lipid molecules in the polar serum. Hence it is made up of an amphipathic outer layer made up of cholesterol and phospholipids, they will be arranged in such a way that the polar hydroxyl group of the cholesterol and phosphate moiety of phospholipids will face outside, enabling them to be soluble in serum and the nonpolar groups will face to the interior in such a way that they carry the triglycerides and cholesterol ester in the interior core.
c. Chylomicrons, which is intended to carry exogenous triglycerides from intestine to the extrahepatic tissues are synthesized in the intestine.
d. They are the least dense lipoprotein with highest triglyceride content. (Density is inversely proportional to triglyceride content).
e. The apoprotein present in nascent chylomicron is apo B 48.
f. Nascent chylomicron after getting apoC II and apoE from HDL becomes chylomicron.
g. Apo CII activates lipoprotein lipase of the blood vessels, thereby giving off their triglycerides to the extrahepatic tissues and thereby becomes chylomicron remnants, which will be accepted by the remnant receptor of liver.
h. VLDL, which is intended to carry endogenous triglycerides (synthesized in the liver), to extrahepatic tissues are synthesized in the liver
i. They are the more dense than chylomicrons but less dense than other lipoproteins.
j. The apoprotein present in nascent VLDL is apo B100. It gets apo C II and apo E from HDL, thereby becoming functional lipoprotein, activates lipoprotein lipase, gives trilycerides to peripheral tissues, and becomes IDL with two apoproteinsapo B100 and apo E.
k. IDL has two fates:
l. It will be accepted by the remnant receptor of liver (or)
m. It will accept cholesterol ester from HDL (involved in reverse cholesterol transport) with the help of cholesterol ester transfer protein and gives back apo E forming LDL.
n. LDL involved in cholesterol transport has only one apoprotein, apo B100 and it will either be accepted by liver or extrahepatic tissues.