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unit 6: MCP > Blood lipoproteins 18 > Flashcards

Blood lipoproteins 18 Flashcards

1
Q

Which lipoprotein has the lowest density?

A

chylos

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2
Q

Which lipoprotein has the highest percentage of lipid and lowest protein content?

A

chylos

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3
Q

Which apoprotein is synthesized in the intestine and not the liver?

A

Apo-B-48

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4
Q

Where are chylos assembled?

A

intestinal muscosal cells

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5
Q

What is the function of a chylo?

A

carries TAG, cholesterol, fat soluble vits, CEs from intestine to peripheral tissues

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6
Q

What apoprotein is unique to chylos?

A

Apo-B48

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7
Q

What apoprotein is apo B 48 a truncated form of?

A

Apo B 100

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8
Q

What process is Apo-B-48 involved in?

A

chylomicron metabolism

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9
Q

What protein loads ApoB48 with lipids?

A

microsomal triglyceride protein - MTP

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10
Q

When the nascent chylo reaches the blood, which apo proteins does it receive?

A

APO-E

Apo CII

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11
Q

What activates lipoprotein lipase?

A

Apo C II

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12
Q

What does lipoprotein lipase do?

A

breaks down TAGs –> FAs or glycerol

  • FAs stored in adipocytes or used for E in muscle
  • glycerol is used by liver - gluconeogenesis

lipoprotein particle dec in size, inc in density

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13
Q

What apoprotein is returned to HDL? what forms as a result ?

A

apo C II is returned to HDL creating a chylo remnant

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14
Q

What binds to what to initiate the liver taking up chylo remnants?

A

Apo E binds to specific LP receptors

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15
Q

What are the two domains of lipoprotein lipase?

A

N terminal domain - lipolytic site

C terminal domain - binds LP particle and gives substrate specificity

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16
Q

How does insulin affect LPL expression?

A

adipose - increased

Muscle - decreased

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17
Q

What is Type 1 Hyperlipoproteinemia or familial LPL?

A

deficiency of LPL or apo CII

  • -acumulation of chylo TAG in plasma
  • higher risk for pancreatitis
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18
Q

Where are VLDLs produced?

A

liver

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19
Q

Nascent VLDLs contain what lipoprotien?

A

apoB 100

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20
Q

What apoproteins do VLDLs obtain from HDL?

A

apoE and ApoCII

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21
Q

TAGs are transferred from VLDL to HDL in exchange for what? What enzyme facilitates this?

A

in exchange for cholesterol esters

CTEP

22
Q

What is the function of VLDL?

A

carries lipids from liver to peripheral tissues

23
Q

VLDL is converted to what in the blood?

A

LDL with IDL or VLDL remnants

24
Q

What is hepatic steatosis or nonalcoholic fatty liver?

A

imbalance btwn TAG synthesis and secretion of VLDL

25
Q

What is the most common isoform of apoE? least common?

A

most = 3

least =2

26
Q

What is familial type III hyperlipoproteinemia?

A

homozygous for ApoE2
-deficient in clearance of chylos or IDL

hypercholesterolemia and premature atherosclerosis

27
Q

What does having ApoE4 put you at risk for?

A

alzheimers - inc susceptibility, decreased age of onset

28
Q

How are LDL particles structurally different than VLDL?

A

much less TAG

more cholesterol and cholesterol esters

29
Q

What is the function of LDLs?

A

provide cholesterol to peripheral tissues and return to the liver

30
Q

What do LDL receptors recognize?

A

apoB100 and apoE

31
Q

What is type II hyperlipidemia?

A

familial hypercholesterolemia
deficiency of LDL receptor
elevated plasma LDL cholesterol

32
Q

After LDLs are taken up by clathrin coated pits, what happens in the endosome to uncoulple the particle from its receptor?

A

pH drops - ATP dependent proton pump

33
Q

An oversupply of cholesterol has what two effects?

A
  1. dec expression of HMG CoA reductase -liver
    - rate control step in cholesterol synthesis
  2. dec expression of liver LDL receptor - liver
34
Q

What happens to cholesterol if it is not needed?

A

esterified by ACAT

-can be stored in the cell

35
Q

What are the six regions of the LDL receptor?

A
  1. LDL binding region - acidic residues
  2. EGF / transducin B - propeller??
  3. N -linked oligo domain
  4. O-linked oligo domain
  5. alpha helical pass
  6. cytosolic domain
36
Q

Genetic mutations in the LDL receptor are of what type mostly?

A

mainly deletions

37
Q

Nascent HDLs contain what apoproteins and are what shape?

A

discoid shape

Apo A1, CII, E

38
Q

What is the function of HDL?

A

takes up cholesterol from peripheral tissues and returns to liver as cholesterol esters

39
Q

What occurs in reverse cholesterol transport?

A
  1. influx of cholesterol peripheral tissue-> HDL
  2. esterification by LCAT
  3. binding of cholesterol ester rich HDL2 to liver
  4. transfer of cholesterol esters to hepatocytes
  5. release of lipid depleted HDL3
40
Q

What is the function of esterification in reverse cholesterol transport?

A

mantains the cholesterol gradient

-allows further uptake from tissues to HDL

41
Q

What is tangier disease?

A

absence of HDL particles

-no efflux of cholesterol by peripheral tissues - ABCA1

42
Q

The uptake of cholesterol esters from the liver involves what receptor?

43
Q

What enzyme in the liver degrades the TG and phospholipids of the HDL?

A

hepatic lipase

44
Q

What does LDLR-related protein recognize?

A

apoE but not apoB100

  • chylo remnant receptor
  • DOES NOT recognize LDL
45
Q

Where is scavenger class A receptor found and what does it recognize?

A

macrophages

recognizes oxidized LDL

46
Q

Does high cholesterol suppress scavengers?

47
Q

When macros consume excess oxidized LDL what do they become?

A

foam cells

48
Q

What do foam cells stimulate by secreting cytokines?

A

migration of smooth muscle cells from media to intima where they proliferate, produce collagen, take up lipids

49
Q

Does the concentration of plasma LPs predict the development of CVD?

50
Q

How is VLDL calculated?

A

TG/5 (20% cholesterol)

not valid if TG > 400

51
Q

does a higher or lower total cholesterol/HDL indicate a high cardiovascular risk?

A

lower number

balance of transport to peripheral tissues/ reverse transport to the liver

52
Q

What are optimal levels for:

  1. Total cholesterol
  2. TG
  3. LDL
  4. HDL
  5. Non-hdl
  6. TC/HDL
A
  1. TC 50 - female , >40 male

5. Non-HDL <4

unit 6: MCP (17 decks)

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