LIPIDS 2 Flashcards by Unknown Unknown

LIPOPROTEINS
Typically spherical in
shape and range in size
_____ - _____ nm

10 to 1200 nm

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Composed of both
lipids and proteins,
called __________

Apolipoproteins

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Larger LPP particles have larger core
regions (contain relatively more TAG and
cholesteryl ester)

Lipoproteins

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The larger the LPP, the more lipid relative to
CHON, therefore, lighter in density

Lipoproteins

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Classifications of lipoproteins based on centrifugation

chylomicrons
very low density lipoprotein
low density lipoprotein
high density lipoprotein

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location of apolipoprotein

surface of LPP particles

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Functions of apolipoproteins

– Help maintain the structural integrity of LPP
– Serve as ligands for cell receptors
– Act as activators and inhibitors of the various
enzymes that modify LPP particles

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Contain “Amphipathic helix”

Apolipoproteins

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– Major protein on HDL

Apo A-I

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– Measure of anti-atherogenic HDL present in
plasma

Apo A-I

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– Is a large protein with MW 500 kD
– Principal protein on LDL, VLDL, and
Chylomicrons

Apo B

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two types of Apo B

Apo B-100
Apo B-48

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is found on LDL and VLDL
– Ligand for the LDL receptor

Apo B 100

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– Exclusively found in chylomicrons

Apo B 48

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Found in LDL, VLDL, and HDL
– Serves as a ligand for the LDL receptor and the chylomicron
remnant receptor
– Apo E2, Apo E3, Apo E4

Apo E

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Contain apo B-48

CHYLOMICRONS

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Account for the turbidity of postprandial
plasma

CHYLOMICRONS

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Readily float to the top of stored plasma
and form a creamy layer

chylous, turbid, milky, cloudy, lipemic
plasma/serum

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Produced by the intestine

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Deliver dietary (exogenous) lipids to
hepatic and peripheral cells

CHYLOMICRONS

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Contain apo B-100, apo E, and apo C

VERY LOW DENSITY LIPOPROTEIN

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Rich in TAG like chylomicrons

VERY LOW DENSITY LIPOPROTEIN

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Account for most of the turbidity observed in fasting hyperlipidemic
plasma specimens but do not form a top, creamy layer

VERY LOW DENSITY LIPOPROTEIN

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Major carriers of endogenous (hepatic derived) triglycerides

VERY LOW DENSITY LIPOPROTEIN

* Transfer TAG from the liver to peripheral tissue

VERY LOW DENSITY LIPOPROTEIN

* Contains apo B-100 and apo E

LOW DENSITY LIPOPROTEIN

Primarily formed as a consequence of the lipolysis of VLDL

LOW DENSITY LIPOPROTEIN

Readily taken up by cells via the LDL receptor – Accounts for the reason that elevated LDL levels promote atherosclerosis

LOW DENSITY LIPOPROTEIN

* Significantly smaller than VLDL and chylomicrons

LOW DENSITY LIPOPROTEIN

* Smallest and the most dense

HIGH DENSITY LIPOPROTEIN

* Synthesized by both the liver and intestine

HIGH DENSITY LIPOPROTEIN

* Can exist either as disk-shaped or as spherical-shaped particles

HIGH DENSITY LIPOPROTEIN

– Most active form in removing excess cholesterol from peripheral cells

* DISCOIDAL HDL

* Larger in size and richer in lipid than HDL3 * May be more efficient in delivering lipids to the liver

– HDL2

2 types of SPHERICAL HDL

HDL2 and HDL3

minor lipoproteins

* Intermediate Density Lipoprotein * Lipoprotein (a)

abnormal lipoproteins

* LpX Lipoprotein * ẞ-VLDL Lipoprotein or Floating ẞ Lipoprotein

Formed through the metabolism of VLDL in circulation; lipid content, size, and density of IDL is intermediate between VLDL and LDL

Intermediate Density Lipoprotein

is similar to LDL in terms of density and overall composition, and can be thought of as an LDL particle to which apo(a) has been added, linked to apoB-100 via a disulfide bond

Lipoprotein (a)

is an abnormal lipoprotein that accumulates in type 3 hyperlipoproteinemia

ẞ-VLDL Lipoprotein / Floating ẞ Lipoprotein

DYSLIPIDEMIA 2 categories

– Hyperlipoproteinemias – Hypolipoproteinemias

3 SUBDIVISIONS:HYPERLIPOPROTEINEMIA

hypercholesterolemia hypertriglyceridemia combined hyperlipidemia

* Most closely linked to heart disease * Increased in LDL cholesterol * Genetic abnormalities

- Hypercholesterolemia

- Individuals synthesize intracellular cholesterol normally, but lack, or are deficient in, active LDL receptors

FAMILIAL HYPERCHOLESTEROLEMIA

-cholesterol deposits on the backs of the hands, knuckles and the Achilles tendon

Tendon xanthomas

which are cholesterol deposits in the cornea

Arcus

is important

Family screening

Causes premature CAD

Familial Hypercholesterolemia:

Result of an imbalance between synthesis and clearance of VLDL in the circulation

– Hypertriglyceridemia

* Life-threatening abnormality because it can cause acute and recurrent pancreatitis

– Hypertriglyceridemia

Presence of elevated levels of serum total cholesterol and triglycerides * Considered at increased risk of CHD

– Combined Hyperlipoproteinemia

Are abnormalities marked by decreased lipoprotein concentrations

HYPOLIPOPROTEINEMIA

HYPOLIPOPROTEINEMIA 2 types

– Hypoalphalipoproteinemia – Hypobetalipoproteinemia

– Indicates an isolated decrease in circulating HDL – Tangier Disease

Hypoalphalipoproteinemia

* mutations in the ABCA1 gene or the ABCA1 transporter, which mediates the first step of the reverse cholesterol transport pathway

HYPOLIPOPROTEINEMIA

LCAT deficiency 2 types

Complete (homozygous) and – Mild (heterozygous)

The ability of HDL to remove cholesterol from cells called

reverse cholesterol transport

is one of the main mechanisms proposed to explain the antiatherogenic property of HDL

reverse cholesterol transport