BIBC 120 Lecture Notes - Lecture 18: Reverse Cholesterol Transport, Lipoprotein Lipase, Cholesteryl Ester
24 May 2018
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Week 7.1
FATTY ACID METABOLISM
1. enterocytes/mucosa package long chain fatty acids into chylomicrons (has
apolipoproteins on the outside)
2. chylomicrons from small intestine mucosa into lymph vessels → slow transfer of
chylomicrons from lymph into blood vessels
3. lipoprotein lipase (Enzyme) attached to endothelial capillary cell lumen (in body tissue)
which catalyzes hydrolysis of TG to free FA → free FA can diffuse to body tissue, glycerol
goes to liver
4. chylomicron continues through body delivering TG to body tissue and it gets smaller →
becomes chylomicron remnant (cholesterol), goes to liver
• Liver makes VLDL [transport dietary FA and other sources like FA synthesized from
glucose from liver to body with help of lipoprotein lipase] ----(loss of TG)--→IDL -----(loss
of TG)----> LDL [deliver cholesterol, cholesteryl esters to the body] taken up via LDL
receptors
o main delivery site of VLDL FA is adipose tissues
o main delivery site of LDL is liver, adipose, muscle
• liver and small intestine make HDL [pick up excess cholesterol from nonliver cells and
deliver it to the liver = reverse cholesterol transport]
• small intestine makes chylomicrons [delivers FA to the body via lipoprotein lipase]
• chlyomicrons vs. VLDL
o chylomicrons – packaged and released in enterocytes in small intestine from
dietary FA, delivery vehicle for FA throughout the body/muscle, end –
chylomicron remnant (cholesterol which gets uptaken by liver)
o VLDL delivery vehicle for FA synthesized by the liver mostly go to adipose tissue
– end product: LDL which has mostly cholesterol, LDL uptaken by liver through
binding of apolipoprotein with receptor
o different apolipoproteins on the outside
• ApoB-100 on LDL binds to LDL receptors, different apoprotein on chylomicron which
binds to different receptor on liver
• Serum LDL and HDL concentrations are interrelated
HDL goes where at the end? takes Ch to other cells that need it or back to the liver through
exchange with LDL (HDL gives Chl to LDL, LDL gives TG) which goes back to liver
• picture: high serum cholesterol, high LDL → less cholesterol in the liver less HDL CHECK
high serum cholesterol – less HDL, more LDL
HEALTH EFFECTS OF LIPIDS
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