Lipid transport Flashcards
2% of lipids are carried in the blood bound to ……
Albumin
What are the components of a lipoprotein?
Peripheral apolipoproteins, integral apolipoproteins, phopholipid monolayer and a cargo
Which lipoprotein classes carry TAGs?
Chylomicron and VLDL
Which lipoprotein classes carry cholesterol esters?
IDL, HDL and LDL
What are the roles of apolipoproteins? (2)
- Packaging water insoluble lipid
- Co-factor for enzymes and ligands for cell surface receptors
apoB is found on which three lipoproteins?
VLDL, IDL and LDL
apoA1 is found on which lipoprotein?
HDL
apoC is found on chlyomicrons and VLDL. What does it bind to?
Lipoprotein lipase
Where do chylomicrons and VLDL release their cargo?
Muscle and adipose tissue
What is the issue of LDL’s having a long half-life?
They are much more susceptible to oxidative damage. When taken up by macrophages this can lead to athreosclerosis.
Which apolipoprotein found on LDL’s acts a ligand for LDL uptake receptors?
apoB-100
How are LDL’s formed?
Through the degradation of VLDL’s and then IDL’s
Where are HDL’s synthesised?
The liver
The ABCA1 protein protein within cells facilitates the transfer of HDL to cholesterol. True or false?
False. The protein helps cholesterol transfer to the HDL.
Where is mature HDL taken up?
The liver
What is hypercholesterolaemia?
It is high levels of cholesterol in the blood
What are the clinical signs of hypercholeestrolaemia?
- Xanthelasma -> yellow patches on eyelids
- Tendon Xanthelasma -> Tendon nodules
- Corneal arcus -> Obvious white circles around the eyes
How are foam cells formed?
When macrophages engulf oxidised LDL
Where do foam cells accumulate to form atherosclerotic plaques?
The intima of blood vessel walls
What is the role of LDL’s?
To transport cholesterol synthesised in the liver to tissues
What is the role of HDL’s?
Transport of excess cholesterol from cells to the liver for disposal as bile salts and to cells requiring additional cholesterol
What is the role of chylomicrons?
To transport TAGs from the small intestine to tissues
What is the role of VLDL?
Transport of TAGs synthesised in the liver to tissues
Bile sequestreants are used as a treatment of hyperlipoproteinaemis. How do they work?
They bind bile salts in the GI tract. This forces the liver to produce more bile salts using up more cholestrol
How many classes of hyperlipoproteinaemias are there?
5 classes
Why do lipids require to be transported in the blood bound to a carrier?
Because they are insoluble
