Plasma Lipoproteins

Question 1

Lipoprotein Lipase

Answer 1

Adipose Tissue & Striated Muscle
Interacts w/ Chylomicrons and VLDL
via apo C-II

TAG –> 3 fatty acids + Glycerol

Question 2

Hepatic Lipase

Answer 2

Liver, plasma, and macrophages

TAG (or phospholipid) –> 2-monoacylglycerol + 2 free fatty acids

Question 3

This protein, exclusive of its enzymic activity, also acts to bind lipoprotein particles, mediating their interactions with receptors suck as LDL receptor and SRB1.

Answer 3

Hepatic Lipase

Question 4

Lecithin: Cholesterol Acyl Transferase (LCAT)

Answer 4

HDL: made in liver, activated by apo A1

lecithin + cholesterol –> lysolecithin + cholesterol ester

Question 5

Cholesterol Ester Transfer Protein (CETP)

Answer 5

shuttles various lipids b/w lipoproteins, resulting in the net transfer of cholesterol esters from atheroprotective, HDL to atherogenic LDL/VLDL.

Question 6

Inhibition of CETP

Answer 6

raises HDL and may potentially be used to treat CVD

Question 7

structure of CETP

Answer 7

long tunnel and four bound lipid molecules

Question 8

ABCA1 transporter

Answer 8

macrophages (esp. foam cells), brain, liver, adrenal, etc.

cell membrane protein that mediates the transport of cholesterol, phospholipids, and other metabolite from cells to lipid-depleted HDL

Question 9

essential for formation of HDL (rate limiting step)

Answer 9

ABCA1 (ATP Binding Cassette transporter)

Question 10

HDP Major apolipoproteins

Answer 10

A-I and E

also A-II, C-1, C-II, C-III, D

Question 11

Where is HDL synthesized? what does it contain?

Answer 11

synthesized in the liver

contains apoA-1, and A-II

Question 12

Esterifies cholesterols of HDL

Answer 12

LCAT (Lecithin Cholesterol Acyl Transferase)

Question 13

HDL acts as a reservoir for

Answer 13

apoC-II and E - it donates them to VLDL and chylomicrons as they are encountered in circulation

Question 14

As HDL acquires more cholesterol esters…

Answer 14

transforms from HDL 3 to HDL 2, then interacts with a special receptor on the liver, SRB1 (scavenger receptor type B1

Question 15

SRB1

Answer 15

facilitates the removal of the cholesterol esters and returns HDL to circulation

Question 16

Apo E is recognized by ____

Answer 16

LDL receptor, so HDL may also be internalized via this route

Question 17

Why is HDL referred to as “good” cholesterol

Answer 17

it removes cholesterol from peripheral tissues and is associated with lowered risk of atherosclerosis

Question 18

carries exogenous lipids

Answer 18

chylomicrons

Question 19

low in protein, phospholipid, cholesterol
high in TGs
carries endogenous lipids

Answer 19

VLDL

Question 20

antiatherogenic effects of ___ are not only dependent on its concentration in circulating blood but also on its

Answer 20

HDL; biological ‘quality’

Question 21

Chylomicron characteristic apolipoproteins

Answer 21

B-48, C-II

Question 22

Chylomicrons

Answer 22

carry dietary fat (TAG’s and cholesterol) from the gut. They are synthesized in the intestinal mucosa and delivered via the thoracic duct into the venous circulation

Question 23

In capillaries of muscle and adipose, ___ recognizes the ____, and removes TAGs

Answer 23

LPL (lipoprotein lipase)

apoC-II

Question 24

depleted of TAGs and apoC-II, ____ are taken up by the liver where the remaining TAGs and cholesterol are incorporated into ____

Answer 24

remnant chylomicrons

VLDL

Question 25

this family of lipoproteins caries TAGs and cholesterol TO the peripheral tissues FROM the Liver

Answer 25

VLDL/IDL/LDL

Question 26

Lipoprotein(a)

Answer 26

Lp(a) is a variant of LDL with an additional protein, apo(a), linked by sulfhydryl bond to apoB-100

Question 27

Independent risk factor for atherosclerosis and consequent MI and CVA

Answer 27

Lipoprotein(a)

Question 28

VLDL Major Apolipoproteins

Answer 28

B-100, C-II, E

Question 29

IDL Major Apolipoproteins

Answer 29

B-100, C-II, E

Question 30

LDL Major Apolipoproteins

Answer 30

B-100

Question 31

apoA1

Answer 31

produced in the small intestines and liver | found in chylomicrons and HDL

Question 32

B-100

Answer 32

synthesized in the Liver | VLDL, IDL, LDL

Question 33

B48

Answer 33

synthesized in intestinal epithelium | chylomicrons

Question 34

C-II

Answer 34

activating cofactor for LPL

Question 35

C-III

Answer 35

inhibitor of LPL

Question 36

Apolipoprotein E

Answer 36

synthesized in the liver blocked from interacting with hepatic receptors by the C apolipoprotien Found on *chylomicrons*, VLDL and HDL When present on IDL, poE enhances the interaction of ApoB-100 w/ hepatic LDL receptors