Low-density lipoproteins Flashcards
What percent of the plasma cholesterol is in LDL?
70% of plasma cholesterol is in LDL.
What is the function of LDL?
Provide cholesterol to the peripheral tissues (or return it to the liver).
What apolipoproteins are there on the surface of LDL?
Apo B-100 and Apo E
What are LDL receptors?
They are negatively charged glycoproteins.
What is the cause of Type IIa Hyperlipidemia?
Any defect in the synthesis of the functional LDL receptors.
Plasma LDL-C levels are high (familial hypercholesterolemia) and premature atherosclerosis
What are the two causes of Autosomal Dominant hypercholesterolemia?
- Defect in Apo B-100
- Increased activity of a protease, proprotein convertase subtilisin/kexin type 9 (PCSK9) which causes lysosomal degradation of the receptor.
What is Wolman disease?
Type of lysosomal storage disease with reduced ability to hydrolyze lysosomal cholesterol ester
What is Niemann-Pick disease?
Reduced ability to transport cholesterol out of the lysosomes.
What does ACAT (acyl CoA: cholesterol acyltransferase) do?
It esterifies the cholesterol in the cell if the cholesterol is NOT needed. Its activity is enhanced when high intracellular cholesterol is present.
What are foam cells?
The macrophages have scavenger receptors that eat LDL (chemically modified), as a result, cholesterol esters accumulate in the macrophages. They participate in the formation of atherosclerotic plaque.
