What are the sources of triglyceride-rich lipoproteins?

Updated: Dec 19, 2019
  • Author: Mary Ellen T Sweeney, MD; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

Triglyceride-rich lipoproteins come from 2 sources, often described as the endogenous and exogenous pathways. In the exogenous pathway, dietary fats (triglycerides) are hydrolyzed to free fatty acids (FFAs) and monoglycerides and are absorbed, with cholesterol, by intestinal cells. They are then reesterified and combined with apolipoproteins and phospholipids to form a nascent chylomicron, a process requiring microsomal triglyceride transfer protein (MTP). The initial apolipoproteins are apolipoprotein (apo) A, which are soluble and can transfer to HDL; and apo B48, a structural apolipoprotein that is not removed during catabolism of the chylomicron. Chylomicrons enter the plasma via the thoracic duct, where they acquire other soluble apolipoproteins, including apo CI, apo CII, apo CIII, and apo E, from HDL.


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