Lipid Transport Flashcards
Where are lipids transported to?
Gut -> Liver -> non hepatic tissue (inc. adipocytes) -> Liver
What is the composition of fats and lipids in circulation?
Triacylglycerides - 45%
Cholesterol esters - 15%
Phospholipids - 35%
Free Fatty acids - 5%
What are fatty acids made of?
Triglycerides
Which factor alters the plasma composition?
Nutritional state
What are the components of a lipoproteins?
- Phospholipids
- Cholesterol
- Cholesterol esters
- Triacylglycerides
What is an apolipoprotein?
A protein that binds a lipid prosthetic group to form lipoproteins
Fatty acids also help regulate thermogenesis, explain how?
Increase expression of UCP-2 and UCP-3 in mitochondria => increases thermogenesis
Why can fatty acids not circulate the body unbound?
They would act as a detergent
What is an apoprotein?
A protein that binds a prosthetic group to form a hormone or enzyme
When does fatty acid saturation occur?
At about 2mM fatty acid molecules
How are fatty acids stored?
In adipose tissues
Why are different components significant?
Each component has a different function
How are Lipoproteins transported?
Via blood as plasma lipoproteins
How do fatty acids circulate the body?
Bound to a protein (albumin) as a Na+ salt
What role do Fatty acids play energy metabolism?
Fatty acids (esp. polyunsaturated FA) are ligands for TFs involved in energy metabolism e.g. insulin metabolism regulation
What is the role of Apolipoproteins?
Transport lipids through lymphatic and circulatory system
How do dietary lipids enter circulation?
- Triglycerides hydrolysed by lipases => FA + monoacylglycerides
- Monoacylglycerides + FA transported across lumen membrane into
Mucosal cell - Converted to triacylglycerides
- Triacylglyceride -> chylomicrons + lipids + proteins
- Chylomicrons enter lymphatic system
List the apoproteins associated with the different Lipoproteins
- Chylomicrons: B48, APO C2, C3 and E
- VLDL: B100, apo C1, C2, C3 and E
- IDL: B100, APO E
- LDL: B100
- HDL: APO A1, A2, C1, C3, D and E
How do Fatty acids regulate insulin metabolism?
- Upregulate lipid oxidation in liver and muscle
- Down regulate lippogenesis genes in liver and adipose tissues
What is a common factor between the constsituents of the plasma?
They are all insoluble in water
List the 5 types of lipoproteins
- Chylomicrons
- Very Low Density Lipoproteins (VLDL)
- Intermediate Density Lipoproteins (IDL)
- 4.Low Density LIpoproteins (LDL) - HIgh Density Lipoproteins (HDL)”
What is the intracelluar concentration of fatty acids normally?
Conc. kept low
What are the functions of apoproteins?
- Structure
- Solubilise lipids
- act as enzymes / cofactors
- tissue targetting
How does VLDL acquire APO C and E?
VLDL made with only APO B100 apoprotein so acquires C and E from HDL as it circulates
