Lipoprotein Flashcards
1
Q
APOC2 activates what enzyme?
A
LPLase
2
Q
ApoA activates what enzyme?
A
LCAT
3
Q
Hepatic SR-B1 removes what?
A
- removes mature HDL from circulation
- binds HDL particles with high affinity
- not down-regulated by high intracell cholesterol levels
- expressed in liver & steroidogenic tissues (adrenal glands & gonads)
- SR-B1 also transports LCFA (has FA translocase properties)
4
Q
Paraoxonase activity on oxLDL
A
- inhibits oxidative mod of LDL
- transported in plasma as component of HDL
5
Q
LCAT fx?
A
- transfers a FA from PtdCho (C-2 lecithin) to cholesterol (C-3) by Entrapment
- Cholesteryl esters, now totally hydrophobic, accumulate in the interior of the HDL particle.
- LCAT activation require interaction of Apo-A1 (synthesized by enterocytes and hepatocytes)
- reduces free cholesterol levels
- regulates composition of plasma lipoproteins & indirectly cholesterol content of membranes
6
Q
ACAT fx
A
- Acyl CoA: cholesterol acyltransferase (cytoplasmic) synthesises cholesteryl esters from free cholesterol on cytoplasmic face of ER
7
Q
Apo-A1: sites of synthesis & fx
A
- sites of synthesis: intestines & liver
- activates LCAT
- structural in HDL
8
Q
Apo-A2: sites of synthesis & fx
A
- sites of synthesis: Intestines & liver
- fx: activator of hepatic lipase
9
Q
Apo-B100: sites of synthesis & fx
A
- sites of synthesis: liver
- fx: structural (in LDL & VLDL) & receptor binding
10
Q
Apo-B48: sites of synthesis & fx
A
- sites of synthesis: intestines
- fx: structural (in chylomicrons)
11
Q
Apo-C1: sites of synthesis & fx
A
- sites of synthesis: liver
- fx: possible cofactor for LCAT
12
Q
Apo-C2: sites of synthesis & fx
A
- sites of synthesis: liver
- fx: activator of LPLase
13
Q
Apo-C3: sites of synthesis & fx
A
- sites of synthesis: liver
- fx: possible inhibitor of LPLase
14
Q
ApoE: sites of synthesis & fx
A
- sites of synthesis: liver & intestines
- fx: receptor binding
