True about apoprotein-C is(AIPG 2008)
|A||Apoprotein A-I and A-II inhibits LCAT|
|B||Apoprotein C-I activates Lipoprotein lipase|
|C||Apoprotein C-II activates Lipoprotein lipase|
|D||Apoprotein C-III activates Lipoprotein lipase|
a. Lipoproteins consist of a non polar core and a single surface layer of amphipathic phospholipids and cholesterol molecules.
b. The protein moiety of a lipoprotein is known as an apolipoprotein or apoprotein, constituting nearly 70 %of some HDL and as little as 1%of chylomicrons.
c. The chylomicrons are released by exocytosis from enterocytes into lacteals, lymphatic vessels originating in the villi of the small intestine, and are then secreted into the bloodstream, at the place where the lymphatic system falls into the blood stream, at the thoracic duct ’s connection with the left subclavian vein.
d. Apolipoproteins carry out several roles:
i. They can form part of the structure of the lipoprotein, e.g., Apo B;
ii. They are enzyme cofactors, e.g., C-II and apo C-III for lipoprotein lipase, A-I for lecithin cholesterol acyltransferase, or enzyme inhibitors, e.g., Apo A-II and apo C-II for lipoprotein lipase, apo C-I for cholesteryl ester transfer protein; and They act as ligands for interaction with lipoprotein; receptors in tissues, e.g., apo B-100 and apo E for the LDL receptors,1po E for the LDL receptor – related protein ((LRP),which has been identified as the remnant receptor, and apo A-I for the HDL receptor.
iii. The functions of apo A-IV and apo D, however, are not yet clearly defined, although apo D is believed to be an important factor in human neurodegenerative disorders.