Lipoprotein Metabolism Flashcards

1
Q

What is the lipid element of a lipoprotein made of?

A

Surface coat - phospholipid + cholesterol

Inner core - triacylglycerol + cholesterol ester

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the function of the apolipoprotein?

A
  • structural
  • enzyme inhibitors/activators
  • recognition factors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Which lipoprotein is the largest and which is the smallest?

A

Chylomicrons –> VLDL –> IDL –> LDL –> HDL

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the three lipoprotein pathways?

A
Exogenous pathway
Intestine --> other tissues
Endogenous pathway 
Liver --> other tissues
Reverse cholesterol pathway
Other tissues --> liver
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Lp(a) and what is it associated with?

A

LDL particle with apo(a)

High amounts associated with aortic stenosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two forms of apolipoprotein B and what do they do?

A

ApoB 100 - LVLDL, IDL, LDL
ApoB 48 - chylomicron and remnants

maintaining structural integrity of particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is MTP?

A

Microsomal triglyceride transfer protein

- expressed in intestine and liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does MTP do?

A
  • catalyses the movement of TAG and cholesterol ester between phospholipid membranes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does the LDL receptor pathway work?

A
  • Receptors in ‘pits’ on membrane LDL
  • Most receptors are recycled, some lost
    - lost receptors replaced by synthesis of new ones
  • Accumulation of cholesterol in cell inhibits transcription of LDL receptor genes –> reduces production of new receptors -> number of receptors decreases
    - Less LDL uptake –> more LDL in blood
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does reverse cholesterol pathway work?

A
  • preB-1 HDL picks up cholesterol from plasma membrane
  • passive mechanism – cholesterol from cell moves into HDL down concentration gradient
  • preB-1 binds to receptor on cell and actively promotes the efflux of cholesterol
  • preB-1 HDL particles fuse together –> preB-2 HDL
    o enzyme LCAT binds to preB-2 HDL particle
    o apoAI activates LCAT –> converts free cholesterol into cholesterol ester
How well did you know this?
1
Not at all
2
3
4
5
Perfectly