Lecture 9- Lipid Transport Flashcards
why do fats need to be packaged and kept soluble
so they can be transported in the blood
what is the role of O-acyltransferase enzymes
transferring an acyl (fatty) acid group
what form is cholesterol most commonly found in
most commonly found in the form of cholesterol ester which is when there is a fatty acid attached
what will inhibit the cholesterol synthesis pathway
if there is a lot of cholesterol coming from the diet
what enzyme is inhibited to inhibit the cholesterol synthesis pathway
HMG CoA reductase
what does HMG CoA reductase do and why is this important
converts HMG CoA to mevalonate = rate limiting step of cholesterol synthesis pathway
where is cholesterol found
in the plasma membrane
what does cholesterol control in the plasma membrane
the fluidity of the membrane
what is the dietary source for cholesterol
animal products
what is cholesterol the precursor for
steroid hormones, bile acids and vitamin D
what is cholesterol a major constituent of
lipoproteins
what is cholesterol important for the transport of
fat soluble vitamins
how is cholesterol important for neuronal function
its a part of the myelin sheath
what is in the middle of the plasma lipoprotein structure
what is on the outside
esterfied cholesterol and triglyceride
Phospholipids and Unesterfied cholesterol
what are the 4 main classes of lipoproteins
chylomicrons
very low density lipoprotein
low density lipoprotein
high density lipoprotein
what is a characteristic of chylomicrons and VLDL
triglyceride rich
what is a characteristic of very LDL and HDL
Cholesterol rich
what is a characteristic of high density lipoprotein
densest because of the high protein content
what do ApoB48 (chylomicrons) and ApoB100 (VLDL) and MTP play a crucial role in
lipoprotein assembly
in the endoplasmic reticulum what is added to ApoB by MTP as it is being made and what does this form
lipids are added to ApoB and this forms a small lipopotein
when a small lipoprotein particle is formed from lipids being added to ApoB, what does MTP add to make the particle bigger
triglycerides
what occurs in the golgi before ApoB is secreted
glycosylation
lipids combine with what via MTP in the ER to form chylomicrons
ApoB
where are chylomicrons secreted from and what do they enter
from intestinal cells entering the bloodstream and lymphatic system
what gives plasma a milky appearance after a fat rich meal and what is this due to
chylomicrons can give plasma a milky appearance due to high triacylglycerol content
chylomicrons and VLDL are metabolised similarly by what
by lipoprotein lipase
what does lipoprotein lipase do and where does this occur
hydrolyses the fatty acids, this occurs at the surface of tissues
what does hepatic lipase (HTGL) do
generates LDL
what dies LRP bind to
apoE
what does LDLR bind to
apoB
what receptor family are LRP and LDLR members of
LDL receptor family
what do LRP and LDLR do
take up remnant IDl and LDL particles
what is the function of lipoproteins
solubilise lipids for transport in blood to tissues
what apoprotein is important for assembly
apoB
what apoproteins are important for ligand cell surface receptors
apoB and apoE
what apoprotein is important for enzyme cofactors
apoCII (for lipoprotein lipase)
what are factors that affect lipids levels
diet = saturated vs unsaturated fats
drugs = fibrates and statins
genetics = defects in lipid metabolism
disease = diabetes
diets rich in what are LDL cholesterol lowering
diets rich in plant sterols
what are mediterranean diets found to reduce
cardiac mortality
eating high amounts of saturated fats can do what
cause LDL levels to increase
what do statins do to LDL cholesterol
lower intracellular levels
so the body makes more receptors
meaning there is more LDL uptake
what does ezetimibe do to LDL cholesterol
less cholesterol coming into the body as decreased intestinal uptake, so more LDL receptors
fibrates and PUFAs both activate a what and what does this bind to and what does this switch on (example)
transcription factor, binds to response element and switching on many genes
one of these is lipoprotein lipase which hydrolyses VLDL and chylomicrons
what would a defect in LPL or apoC-II cause
elevated triglyceride levels
what would a defect in apoB or MTP cause
low blood cholesterol levels
