BPS 334 Lecture Notes - Lecture 34: Microsomal Triglyceride Transfer Protein, Cholesteryl Ester, Lipoprotein Lipase
27 Nov 2016
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How does dietary cholesterol get into the enterocyte: exogenous cholesterol and triglycerides are simultaneously absorbed from the intestinal lumen by different mechanisms, cholesterol is taken up from micelles across a regulatory channel named niemann-pick- C1-like 1 protein (npc1l1: a fraction of the cholesterol is pumped back into the lumen by abcg5/g8, a geterodimeric atp-dependent plasma membrane protein. Therefore, this cholesterol is not getting absorbed so there is not hypercholesterol: the remainder of the cholesterol is converted to cholesteryl esters by acat. Chylomicrons: formed in the intestine and transport dietary triglycerides. Cholesteryl esters in chylomicrons are derived mainly (75%) from biliary cholesterol, with the remainder contributed by dietary sources. Vldl: formed in the liver and transport triglycerides that are synthesized endogenously. Editing apob mrna: key event to differentiate chylomicron and vldl metabolism: the apob gene is transcribed in both the intestine and the liver, in the intestine, but not the liver, a protein complex containing apob editing complex-
