Lipoproteins

Question 1

Most common apoproteins

Answer 1

Apo A1
Apo B48
Apo B100
ApoC2
Apo C3
Apo E

Question 2

Apo A 1

Answer 2

intestine, liver
HDL
activates LCAT, forms structures of HDL, interacts with ABC transporter

Question 3

Apo B48

Answer 3

intestine
chylomicrons
assembly of chylomicrons from small intestine, cholesterol transport/clearance

Question 4

Apo B100

Answer 4

liver
VLDL,IDL,LDL
VLDL assembly + secretion, structural portion, binds LDL receptor

Question 5

Apo C2 and Apo C3

Answer 5

Apo C2:
liver
chylomicrons,VLDL,IDL,HDL
activates LPL

APO C3:
liver
chylomicrons, VLDL, HDL
inhibits LPL

Question 6

Apo E

Answer 6

liver
chylomicrons remnant, VLDL, IDL, HDL
ligand for binding, triggers clearance of VLDL

Question 7

Chylomicrons

Answer 7

largest, least dense
produced in fed state in intestinal epithelial cells
delivers dietary lipids
main apo proteins: B48, C2, E
accepts proteins from HDL to mature

Question 8

VLDL

Answer 8

produced in liver in fed state
deliver endogenous lipids
main apoproteins: B100, C2, E

Question 9

IDL

Answer 9

VLDL remnant
can be acted upon by hepatic TG lipase, converts to LDL
function: LDL precursor, returns endogenous lipids to liver
main apoproteins: B100, E

Question 10

LDL

Answer 10

IDL remnant
made in blood
function: transport cholesterol to peripheral tissues
main apoproteins: B100
endocytosed by liver and peripheral tissue(60% back ti liver)

Question 11

High amount of LDL in blood

Answer 11

scavenger cells get LDL oxidized
forms foam cells
accumulated and forms atherosclerotic plaque

Question 12

HDL

Answer 12

smallest, most dense
produced in liver, intestines
has LCAT
function: reverse cholesterol transport, exchanges apoproteins with other lipoprotein particles
main apoproteins: A1, C2, E

Question 13

LCAT

Answer 13

Lecithin cholesterol acyl transferase

• in HDL
• cholesterol + phosphatidylcholine -> cholesterol ester + lysolecithin

Question 14

Cholesterol ester transfer protein

Answer 14

With it HDL can exchange CE with TG with VLDL

Question 15

LPL

Answer 15

lipoprotein lipase
in heart: Km for TG low
in adipose tissue: Km for TG high
during starvation heart enzyme, lactating mammary gland enzyme remains saturated

Question 16

Genetic disorders

Answer 16

Lipoprotein lipase deficiency:

• LPL defect
• chylomicrons, VLDL elevated

Familial apoC2 deficiency:

• Apo c2 defect
• chylomicrons, VLDL elevated

Familial hypercholesterolemia:

• LDL-receptor defect
• LDL elevated