Lipoprotein

Lipoprotein

• Apolipoproteins

• Lipoproteins are macromolecules composed of lipids and proteins.

• In serum, cholesterol is carried primarily on three different lipoproteins—the VLDL, LDL, and HDL molecules.

• Total cholesterol equals the sum of these three components.

• Plasma lipoproteins are important for lipid solubilization in order to:

  • Transport triglycerides, an important energy source, and to transport cholesterol between different places of absorption, synthesis, catabolism, and elimination.

• Chylomicron

  • Apolipoprotein A, B-48, C, E

• VLDL

  • Apolipoprotein B-100, C, E

• IDL

  • Apolipoprotein B-100, E

• LDL

  • Apolipoprotein B-100

• HDL

  • Apolipoprotein A & C

what are lipoproteins? Lipids cover by protein ( by it’s name = lipo prteins) Lipids are insoluable in water – so they cannot dissolve in the blood In order to transport the lipid in the blood it has to be covered by a hydrophilic surfce .. protein – hydrophobi core: cholesterol/TG and hydrophilic surface

`*But why LDL is considered the “bad” one ? It has the highest concentration of cholesterol. *Is cholesterol important ? Yes in synthesis of hormones (estrogen /progesterone/ testosterone ..etc) but it is considered bad if we have high amount of it because it has high cholesterol.

• Why HDL is considered the Good lipoprotein ?

What happens when we eat fatty food?

Chylomicrons

• Origin: enterocytes.
• Released from intestinal epithelial cells.
• Transport of dietary TAG.
• Function: transport lipids to adipose tissue (fatty acids are stored by the adipose) or used for energy (by the muscles).

VLDL

• Origin: liver.
• Secreted by the liver hepatocytes into the blood.
• Transport endogenously synthesized TAG to other tissues.
• Transport lipids from liver to adipose tissue (break down TAG and take it) – where IDL is formed.

LDL

• Origin: plasma
• Formed in circulation by partial breakdown of IDL
• Delivers cholesterol to peripheral tissues,
• Carries cholesterol to (testes/adrenal glands, etc.) for hormones.

HDL

• Origin: Liver
• Removes excess cholesterol from tissues and takes it to the liver.

Excess LDL can increase the risk of Coronary Artery Disease?

Cholesterol and Lipoproteins

• Serum cholesterol and its lipoprotein are known to be related to ASCVD.
• LDL-C is the dominant form of atherogenic cholesterol.
• VLDL is the chief carrier of triglycerides, and VLDL cholesterol (VLDL-C) is also atherogenic.
• *HDL-C is seemingly not atherogenic.